$80 Find Cheap Flights from Ontario to Illinois

This is the cheapest one-way flight price found by a KAYAK user in the last 72 hours by searching for a flight from Ontario to Illinois departing on 8/12. Fares are subject to change and may not be available on all flights or dates of travel. Click the price to replicate the search for this deal.
1 adult
1 adult, Economy, 0 bags

KAYAK searches hundreds of travel sites at once for deals on flights to Illinois

 
These are the airlines KAYAK users have selected most often from within our search results in flight searches from Ontario to Illinois, as well as popular online travel agencies
These are the airlines KAYAK users have selected most often from within our search results in flight searches from Ontario to Illinois, as well as popular online travel agencies
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Cheap Flights from Ontario to Illinois

Cheapest round-trip prices found by our users on KAYAK in the last 72 hours
Chicago
Chicago1 stop$273
Moline
Moline1 stop$349
Peoria
Peoria1 stop$429
Springfield
Springfield2 stops$574
St. Louis
St. Louis1 stop$197
Paducah
Paducah1 stop$647
Chicago
Chicago1 stop$273
Moline
Moline1 stop$349
Peoria
Peoria1 stop$429
Springfield
Springfield2 stops$574
St. Louis
St. Louis1 stop$197
Paducah
Paducah1 stop$647

Book Cheap Ontario to Illinois Plane Tickets

 
Here are some of the best deals found on KAYAK recently from the most popular airlines for round-trip flights from Ontario to Illinois that are departing in the next months. While these flights were available on KAYAK in the last 72 hours, prices and availability are subject to change and deals may expire.
Discover the best prices for you by selecting your travel dates on KAYAK.

Recent round-trip flight deals from Ontario to Illinois

Wed, Aug 12 - Wed, Aug 26
Frontier Logo
6:00 am - 7:23 pm
ONT
-
STL
11h 23m
1 stop
Frontier Logo
8:08 pm - 10:05 am
STL
-
ONT
15h 57m
1 stop
$197Frontier
Wed, Aug 12 - Mon, Aug 31
Frontier Logo
10:49 am - 7:23 pm
ONT
-
STL
6h 34m
1 stop
Frontier Logo
5:33 pm - 11:49 pm
STL
-
ONT
32h 16m
2 stops
$200Frontier
Wed, Sep 9 - Sat, Sep 19
Southwest Logo
1:50 pm - 10:50 pm
ONT
-
MDW
7h 00m
1 stop
Southwest Logo
4:05 pm - 8:05 pm
MDW
-
ONT
6h 00m
1 stop
$273Southwest
Wed, Sep 9 - Sat, Sep 19
American Airlines Logo
2:22 pm - 12:06 am
ONT
-
ORD
7h 44m
1 stop
American Airlines Logo
5:09 pm - 9:37 pm
ORD
-
ONT
6h 28m
1 stop
$273American Airlines
Thu, Sep 24 - Tue, Sep 29
Delta Logo
12:00 pm - 9:46 pm
ONT
-
MDW
7h 46m
1 stop
Delta Logo
9:30 am - 6:01 pm
MDW
-
ONT
10h 31m
2 stops
$277Delta
Tue, Sep 22 - Mon, Sep 28
Delta Logo
7:00 am - 5:22 pm
ONT
-
ORD
8h 22m
1 stop
Delta Logo
3:50 pm - 11:44 pm
ORD
-
ONT
9h 54m
2 stops
$277Delta
Thu, Aug 27 - Sat, Aug 29
Southwest Logo
11:55 pm - 5:45 am
ONT
-
MDW
3h 50mnonstop
Southwest Logo
6:00 pm - 8:10 pm
MDW
-
ONT
4h 10mnonstop
$287Southwest
Sat, Jun 6 - Sat, Jun 13
American Airlines Logo
11:59 pm - 10:39 am
ONT
-
MLI
8h 40m
1 stop
American Airlines Logo
4:24 pm - 10:36 pm
MLI
-
ONT
8h 12m
1 stop
$349American Airlines
Sat, May 30 - Tue, Jun 2
United Airlines Logo
5:45 am - 9:10 pm
ONT
-
PIA
13h 25m
2 stops
United Airlines Logo
4:45 pm - 10:51 pm
PIA
-
ONT
8h 06m
1 stop
$441United Airlines
Thu, May 28 - Tue, Jun 2
United Airlines Logo
1:18 pm - 9:01 pm
ONT
-
PIA
5h 43m
1 stop
United Airlines Logo
4:45 pm - 10:51 pm
PIA
-
ONT
8h 06m
1 stop
$564United Airlines
Booking Insights

KAYAK's insights & trends for Ontario to Illinois flights

Get data-powered insights and trends into flights from Ontario to Illinois to help you find the cheapest flights, the best time to fly and much more.

How much is a round-trip flight from Ontario to Illinois?

This analysis is based on the cheapest round-trip price found on KAYAK in the last 12 months by searching for a flight from Ontario to Illinois departing in September.

What is the cheapest Ontario to Illinois flight route?

Data is based on round-trip flight searches on KAYAK over the past month.

The cheapest ticket to Illinois from Ontario found in the last 72 hours was to Chicago, at $298 round-trip. The most popular route is from Ontario (ONT) to Chicago O'Hare Intl Airport (ORD), and the cheapest round-trip airline ticket found on this route in the last 72 hours was $298.

What is the cheapest time of day to fly to Illinois?

The average price for all round-trip flights from Ontario to Illinois depending on the time of departure, clicked by users on KAYAK in the last 2 weeks.

The cheapest time of day to fly to Illinois is generally at night, when round-trip flights cost $479 on average. The most expensive time of day to fly to Illinois is generally in the afternoon, which is peak travel time and where the average cost of a ticket is $526.

Can I save money by flying with a layover from Ontario to Illinois?

The average round-trip price for all non-stop flights, flights with one layover, and flights with two layovers for the route found by users searching on KAYAK in the last 2 weeks.

Yes, flying with a layover may cost you more time, but you can also save money on the route, with a 2 stops layover the cheapest option at $485 on average.

What is the cheapest month to fly from Ontario to Illinois?

To calculate monthly average prices, KAYAK takes all prices for each month over the last year for round-trip flights from Ontario to Illinois, removes the top 0.1% to account for outliers, and then takes the median of all values for each month.

The cheapest month for flights from Ontario to Illinois is September, when tickets cost $102 (return) on average. On the other hand, the most expensive months are March and May, when the average cost of round-trip tickets is $186 and $186 respectively.

What’s the cheapest day of the week to fly from Ontario to Illinois?

The average price of all round-trip flights from Ontario to Illinois clicked on KAYAK for each day over the last 12 months.

If your flying dates are flexible, you should consider flying to Illinois on a Wednesday, as we generally find the cheapest rates on that day for this route. On the other hand, Sunday is the most expensive day to fly from Ontario to Illinois. For your return ticket, we recommend flying on a Wednesday and avoiding Sundays for the best deals.

How far in advance should I book a flight from Ontario to Illinois?

To calculate weekly average prices, KAYAK takes all prices for each week before departure over the last year for round-trip flights from Ontario to Illinois, removes the top 0.1% to account for outliers, and then takes the average of all the values for each week.

To get a below average price on the flight from Ontario to Illinois, you should book around 4 weeks before departure, which saves you about 37% compared to booking last minute. For the absolute cheapest price, our data suggests you should book 11 weeks before departure.

Good to know

Low seasonJanuary
Cheapest flight$80
Best time to beat the crowds with an average 11% drop in price.
Most popular time to fly with an average 4% increase in price.
Flight from Ontario to Chicago O'Hare Airport

FAQs - booking Illinois flights

  • How does KAYAK find such low prices on flights from Ontario to Illinois?

    KAYAK is a travel search engine. That means we look across the web to find the best prices we can find for our users. With over 2 billion flight queries processed yearly, we are able to display a variety of prices and options on flights from Ontario to Illinois.

  • How does KAYAK's flight Price Forecast tool help me choose the right time to buy my flight ticket from Ontario to Illinois?

    KAYAK’s flight Price Forecast tool uses historical data to determine whether the price for a flight from Ontario to Illinois is likely to change within 7 days, so travelers know whether to wait or book now.

  • What is the Hacker Fare option on flights from Ontario to Illinois?

    Hacker Fares allow you to combine one-way tickets in order to save you money over a traditional round-trip ticket. You could then fly from Ontario to Illinois with an airline and back with another airline.

  • What is KAYAK's "flexible dates" feature and why should I care when looking for a flight from Ontario to Illinois?

    Sometimes travel dates aren't set in stone. If your preferred travel dates have some wiggle room, flexible dates will show you all the options when flying from Ontario to Illinois up to 3 days before/after your preferred dates. You can then pick the flights that suit you best.

Top tips for finding cheap flights to Illinois

  • Looking for a cheap flight? 25% of our users found tickets from Ontario to the following destinations at these prices or less: Chicago $210 one-way - $438 round-trip; Chicago $236 one-way - $411 round-trip

Reviews of the top 5 airlines serving from Ontario to Illinois

 
See real verified KAYAK customer reviews for airlines flying from Ontario to Illinois. Airline scores are aggregated from all reviews left by passengers on KAYAK after flying with an airline. KAYAK doesn’t show reviews that are older than 5 years. Learn how KAYAK collects reviews.
Need help choosing which airline to fly with from Ontario to Illinois? KAYAK airline reviews give an overall score for each airline based on loads of factors, including comfort, boarding, in-flight entertainment and more, to make your decision easier. See airline scores according to verified KAYAK customer reviews.
8.0
SouthwestOverall score based on 4292 reviews
8.0Comfort
8.6Crew
8.1Boarding
7.5Entertainment
7.0Food
Airline reviews

The checking experience in Orlando was terrible, almost missed the flight. Too many travelers and Southwest completely understaffed.

2.0 MediocreAnonymous, May 2026
MCO - MDW
Read more Southwest reviews

The checking experience in Orlando was terrible, almost missed the flight. Too many travelers and Southwest completely understaffed.

The entire experience from boarding to landing was amazing! The crew were very friendly. Will definitely be back.

no service at all due to turbulence. they should've at least given us snacks, there were only 10 people on the entire flight.

Delayed flight, lack of information, boarding process is a mess as is the carryon luggage causing issues when leaving the plane….just a poor experience.

Comfortable. Easy. No problems. Just wish they had gf options for snacks.

The crew was very kind and made going to Hawaii relaxing and fun to look forward to! Thank you Southwest for a pleasant flight!

For the first time in a long time, the Wi-Fi actually worked the entire flight! The flight crew was amazing as usual.

Great flight. I didn't get a drink because I was asleep whole on the flight.

Terrible. Even though there’s assigned seating now, they are still the slowest boarding airline of anyone.

It was good from LAX to Phoenix, But the connection in Phoenix to Tulsa was not that great. The staff on both flights were great. The choice of free entertainment was ok nothing to brag about. The 45 min delay because of some electrical issue wasn't great from Phoenix to Tulsa. We sat there with hardly any air, The seat I had was between windows so the side of the plane pushed in on you. My being a bigger man it then made the seating area uncomfortable. The seats on the plane had no power to connect to recharge your phone or anything. I would recommend that they should look into a slot or clamp to hold your phone to enjoy while watching the entertainment choices hands-free. Also make it possible to raise the inner seat by the window be able to raise the arm rest up to make more room for larger people to set more comfortably. I would also say other then that stop price gouging the airfare or nickel and diming everything. Not fair for people having to fly for emergencies and be paying for higher prices due to the season or holidays. Your making your money either way and the cost of flying is still going to be the same regardless if there's 100 people or 200 people.

While they turned off most cabin lights to allow people to sleep, I was bothered by how bright the side lights still were. It was still quite bright for me in a window seat, when I wish I could have slept!

Generally on time departures and arrivals, clean planes, sky miles membership provides great benefits (complimentary upgrades, etc).

N Everything was perfect from boarding to assistance to baggage in Tampa

Loved the crew! Sucks that we went from 1 hour and 8 minute layover to a 3 hour layover. But weather sucks like that.

Fast, lovely scenery, great info on the Delta flight screen about landmarks we were flying over. Great landing!

Long flight but comfortable and not freezing as I have experienced on Hawaiian flights to the islands. They gave us blankets just in case. Nice touch.

I took seat 15A in anticipation of window seat, there is no window.

Flight late, the waited for a long time for “personal” to arrive at gate to dock the plane in Rochester. So annoying. This flight was expected, why aren’t personel available for the jet bridge?

My recent experience was excellent on Delta! I flew with Delta Comfort and I was really comfortable in my seat. I enjoyed the in-flight service. The flight attendants were so friendly and hospitable. I love the snack on the flight as well. This was my first time flying on Delta and I will definitely consider flying with them again.

My flight was canceled on Sunday. Rebooking took three hours. Had to pay for accommodations another night. New flight was delayed for 5 hours, all that was sent was a 12 dollar food voucher, which doesn’t tell you how to use it. Then when we landed we had to sit on the plane for an hour before we could get off.

O’hsre taxi and deboarding took 40 minutes. Needed 20 minutes extra time between connecting flights to avoid running through terminal.

Standard flight with a drinks and a snack- overall very quick flight. The flight attendants were very strict, bordered on rude.

Delayed - weather wasn't bad at either end. Also sat on tarmac in ORD.

boarded early to only find out that flight would sit at gate for 45 min to an hour. Landed in chicago and sat on runway for over an hour before got to gate. Total delay was extensive for a 45 min flight door to door.

The flight was significantly delayed. The inbound flight from EWR was delayed departing because of mechanical problems. My original departure from CLT was 5:28 pm but due to the delay of the inbound flight, after arrival, deplaning, cleaning, boarding, we did not push back from the gate until 9:00 pm. Once in the air, the flight was smooth and what was originally supposed to be an arrival in ORD at 7:30 pm local time turned out to be 9:35 pm.

The flight I was supposed to be on was supposed to take off at 1:50 from State College. It was delayed over and over and over again until somehow I had to rebook on a flight that was supposed to have left State College at 8 am that morning but didn't end up taking off until almost 6 pm. Not only was this completely unacceptable, the "token from United" was a 15 dollar meal voucher that has to be used by today. I would personally like some miles added to my account for this inconvenience. I was in transit for 8 hours from the time I arrive at State College Aiport to when I got home. I was supposed to be home at 3 pm and I returned at 8 pm. Unacceptable. I have not been on an on Time united flight in nearly 5 years.

newer aircraft, ability to connect my headset via blue tooth for entertainment.

Very comfortable flight, snacks and drinks were good, good communication from crew. Could have used a little more information on timing of boarding for group 5

Great flight. Got to watch a movie. Smooth flight and early arrival at ORD.

It was better than excellent. The staff in Mason City were great. The young woman that pushed my wheelchair did more than could be expected of her. She came from India 17 years ago. I don't remember her name.

It was good, the staff was great, and the food, was as usual, tea and biscuit. Bathroom was clean, and the plane was clean as well.

Very good I can’t complain one bit. Thank you American Airlines for making my flight enjoyable and safe!

The staff and service on American Airlines were truly outstanding. I had requested wheelchair assistance for my mother due to her knee issues, and the team went above and beyond every step of the way—from boarding in Boston to our arrival in Chicago. Their care, professionalism, and attentiveness made the entire experience smooth and stress-free. I’m very grateful for the support they provided.

The new planes (American Eagle) are beautiful and especially comfortable. The flight attendants are consistently professional and courteous. And, while it may seem inconsequential, the new liquid tube of coffee creamer—in contrast to the powdered coffee creamer—makes all the difference in a cup of coffee.

Boarding was quick and efficient. We arrived at our destination early.

I'm not sure American is capable of on-time arrivals and departures. When you land at ORD, you almost always get held on the tarmac because your gate is still occupied. I may have missed my connection, but that ended up up being significantly delayed as well. Once again, I finally got home well after midnight.

Good flight, seated and had a water within 5 minutes. Crew was hospitable.

Crew at the gate was very crabby and not at all polite. The plane was very hot the entire flight. And the seat cushion was very worn out.

The staff are very, very professional. It's what flying should feel like.

Flight was delayed half hour before boarding, but when I checked flight aware the plane that would Pick us up had a delay of more than an hour. AA should let us know in advance to avoid waiting several hours in the airport

Flight was scheduled at 9:40pm. Got delayed to 10 am, the next day. crazy

The bag check, flight check-in, and onboard experience convinced my wife and me that we will actively go out of our way to avoid flying Frontier Airlines in the future. At bag check, we were informed that check-in could only be completed via the Frontier mobile app. Unfortunately, the app was extremely frustrating—sending us through repetitive, confusing loops that repeatedly forced us to decline add-on services with nearly every click. While most airline apps upsell, this one felt intentionally exhausting. As the process dragged on, we became genuinely concerned that my phone battery would die before check-in could be completed. We approached the bag check staff—who were standing together talking—and explained both our frustration and our predicament. They laughed. Later, my wife described the interaction as “gaslighting,” which felt accurate. We were then informed it would cost $25 per person simply to have our boarding passes printed. From that point forward, the tone of the experience was consistently hostile. The bag check employees were condescending and combative, behaving more like bullies than customer service staff. Unfortunately, that same attitude continued onboard. One flight attendant argued with me when I attempted to stow my backpack in the overhead bin. I explained that we had each paid $75 to check our bags specifically so we would not need to use carry-on space and could have adequate legroom. She demanded to see my ticket, pointed out that it said “no carry-on”—which I acknowledged—and I reiterated that this was precisely why we paid to check our bags. Her response was, “I don’t make the rules.” She then walked away, but not before asking if I “truly wanted to fly back to Chicago today?”—an unnecessary and unmistakable threat. It is also worth noting that despite booking our tickets together in the same transaction, we were not seated together. Upon our return to Chicago—where we could once again sit together—we compared onboard experiences. We both remarked on how unhappy the flight attendants appeared and how each of us was separately asked whether we would like to purchase a beverage. We declined. At no point was water mentioned as an option, leaving us with the clear impression that even water came at a cost—or that complimentary water, if available at all, was deliberately left unmentioned. Overall, the experience was shocking and deeply disappointing, but it was also a profound learning experience—one we will not forget and will not repeat. -Steve

They didn’t offer a water, even after I asked

Remind customers of the need to have passport or new ID for boarding.

The flight never took off and we spent 7 hours at the airport

Good for a budget airline! It was easy to get on, staff was really nice. Can’t say anything about the food or entertainment because it wasn’t available, which is fine.

It was ok. It was expensive to check 2 bags ($75.00 per bag), and then it took a long time to wait for shuttle to take us from one terminal to the terminal where the plane was taking off at LAX. And all of this for a flight where we had to pay for any food or drink that was not water.

This company socks. It's fraud. They canceled our flight yesterday, and today we were late because of a really long line at the check in bag. At the rebook station, there was ton of people. The workers were all rude. I am gonna make a report to FTC.

When I wanted to check in 3 hours prior to boarding time, the employees mentioned “a little over an hour delay” so I waited for an hour then I went to go look for food in the terminal and most people from that flight were in the same area looking for food. Finally I decided after food to check to see if it’s anytime closer and now it’s 2 mins until boarding closes?! What are you kidding me? I didn’t receive anything via sms about boarding now nor via email or on the intercom. I luckily made it through, barely, and then there’s no room for my carry on mind you I’m in the very first row so I had to place my purse in one further row back and my carry on sections down. Not sure who pays for better seats to get your stuff placed all over the plane but that was the worst experience I’ve ever had flying with anyone.

The single worst check in experience I could imagine. I’ll never do any business with Frontier or any affiliated company

Everything you need to know for your flight from Ontario to Illinois

Information on your arrival and departure airports