$79 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 4/15. 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$259
Moline
Moline1 stop$369
Peoria
Peoria1 stop$369
Bloomington
Bloomington1 stop$419
Springfield
Springfield2 stops$649
St. Louis
St. Louis1 stop$160
Paducah
Paducah2 stops$440
Chicago
Chicago1 stop$259
Moline
Moline1 stop$369
Peoria
Peoria1 stop$369
Bloomington
Bloomington1 stop$419
Springfield
Springfield2 stops$649
St. Louis
St. Louis1 stop$160
Paducah
Paducah2 stops$440

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

Fri, Apr 17 - Fri, Apr 24
Frontier Logo
5:33 pm - 7:32 pm
ONT
-
STL
23h 59m
1 stop
Frontier Logo
9:58 pm - 6:49 pm
STL
-
ONT
22h 51m
1 stop
$160Frontier
Mon, May 4 - Mon, May 11
Frontier Logo
8:59 pm - 6:06 pm
ONT
-
STL
19h 07m
1 stop
Frontier Logo
9:18 pm - 7:32 pm
STL
-
ONT
24h 14m
1 stop
$162Frontier
Thu, Apr 23 - Sun, Apr 26
Frontier Logo
11:47 am - 9:00 pm
ONT
-
STL
7h 13m
1 stop
Frontier Logo
9:55 pm - 8:24 am
STL
-
ONT
12h 29m
1 stop
$167Frontier
Thu, Apr 23 - Tue, Apr 28
Delta Logo
12:49 pm - 10:28 pm
ONT
-
MDW
7h 39m
1 stop
Delta Logo
6:00 am - 11:36 am
MDW
-
ONT
7h 36m
1 stop
$261Delta
Sat, Apr 18 - Tue, Apr 21
Delta Logo
1:29 pm - 9:18 pm
ONT
-
ORD
5h 49m
1 stop
Delta Logo
7:10 pm - 11:44 pm
ORD
-
ONT
6h 34m
1 stop
$261Delta
Thu, May 7 - Sat, May 9
United Airlines Logo
7:00 am - 1:03 pm
ONT
-
ORD
4h 03mnonstop
United Airlines Logo
3:35 pm - 6:01 pm
ORD
-
ONT
4h 26mnonstop
$266United Airlines
Mon, Apr 27 - Mon, May 4
Southwest Logo
11:55 pm - 5:40 am
ONT
-
MDW
3h 45mnonstop
Southwest Logo
11:00 am - 1:15 pm
MDW
-
ONT
4h 15mnonstop
$284Southwest
Sat, Jun 27 - Sat, Jul 4
United Airlines Logo
6:30 am - 3:12 pm
ONT
-
MLI
6h 42m
1 stop
United Airlines Logo
3:52 pm - 10:51 pm
MLI
-
ONT
8h 59m
1 stop
$369United Airlines
Wed, Apr 8 - Wed, Apr 15
American Airlines Logo
2:08 pm - 11:29 pm
ONT
-
MLI
7h 21m
1 stop
American Airlines Logo
12:52 pm - 9:07 pm
MLI
-
ONT
10h 15m
1 stop
$394American Airlines
Wed, Apr 8 - Wed, Apr 15
American Airlines Logo
12:19 pm - 11:29 pm
ONT
-
MLI
9h 10m
2 stops
American Airlines Logo
12:52 pm - 9:07 pm
MLI
-
ONT
10h 15m
1 stop
$399American 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 April.

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 $296 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 $297.

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 in the morning, when round-trip flights cost $459 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 1 stop layover the cheapest option at $424 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 January, when tickets cost $307 (return) on average. On the other hand, the most expensive months are December and March, when the average cost of round-trip tickets is $543 and $458 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 Thursday, 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 Tuesday and avoiding Saturdays 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 38% compared to booking last minute. For the absolute cheapest price, our data suggests you should book 25 weeks before departure.

Good to know

Low seasonJanuary
Cheapest flight$79
Best time to beat the crowds with an average 11% drop in price.
Most popular time to fly with an average 20% 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 $248 one-way - $424 round-trip; Chicago $239 one-way - $363 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 4331 reviews
8.0Comfort
7.5Entertainment
8.6Crew
8.1Boarding
7.0Food
Airline reviews

Southwest was greaat! The most expensive but the least upsetting for those we were flying to see.

10.0 ExcellentMartie, Mar 2026
LGB - BNA
Read more Southwest reviews

Southwest was greaat! The most expensive but the least upsetting for those we were flying to see.

Boarding was easy. The seats are small and fairly uncomfortable

The problem with the seat assignments is that there were a lot of rows in the front that were empty but my row at the back was full. Just not so pleasant.

Good but I prefer choose your own seat. With the new assigned seats they should board from the back I see no advantage to this new boarding. Just like every other airline

WiFi was not working and didn’t have a beverage service

Flight boarded late after announcing on time boarding. Flight arrived only a little late despite late departure. Had trouble connecting to WiFi

The Southwest experience has definitely taken a dive from its early days. You can no longer deferentiate from other airlines. Air travel is too expensive. Southwest is no longer budget friendly. They have lost me as a loyal customer.

The charges were ridiculous for an hour flight and the turbulence was very scary.

The seats are now more narrow. I paid for front row the seats in the front are even more narrow than before.

The wifi on the plane is great. The only issue that I have is that I prefer an aisle seat and on my trips this week, I was either in the middle or window. If we can work to secure aisle seating, I will be thrilled. Nice trip.

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.

I was in first class and literally the men behind me were so aggressively loud I moved myself to economy. This has become so common on Delta - people using audio without headphones, and men on 12am / late night flights drinking and yelling to talk to each other which prevents anyone around them from resting. Pretty crazy to have to move from first to economy (poorer service, less comfort...). Wild wild. Looking into other airlines.

There was an unruly family behind us that made the short flight miserable!!! The cabin crew did nothing to contain it.

Flight was delayed by 3-hours and their fix was… complimentary pretzels.

The crew, and fellow passengers, were super gracious and kind. There seemed to be plenty of bin space even though the plane was full. It’s nice to get a glass of wine with dinner in Premiere seating, and there was a lot of food.

Everything I mentioned earlier - the airbus was more comfortable indeed and the experience was further enhanced.

3 hour delay…. Nearly 2 hours sitting on tarmac. Do better, United. Or at least have the sense to not say “we hope you enjoyed your flight with us” upon disembarking.

Flights were on time. Free Wifi on plane. Everything was well organized.

Economy plus was so cramped I could not use my laptop. It was beyond bad.

Wonderful. Quick boarding. Early departure and we arrived 30 minutes early at our destination. Unfortunately, when you arrive early, there is still a departing aircraft at our gate. We had to park for 30 minutes until the gate was clear. So our early arrival was not really early at the gate. Otherwise it was a quick and smooth flight. Appreciated the efficiency.

Crew was great (professional, attentive, prompt). Snacks for 4 hrs flight is deplorable.

United Airlines is my preferred airlines and I am thankful for Gary who also help support me on the phone to switch my flight literally last min.

Seated dude next to me even though lots of empty rows. But main thing was we sat on the tarmac after landing for 30 minutes because of, in the words of the dude who sat next to me, “operational incompetence”. We got changing directions about where to pick up gate checked bags. Pilot and flight attendant were awesome though.

It was a pretty standard flight... until the almost hour and a half spent on the taxi way. I get that the weather has been poor but the delay had nothing to do with the weather and more to do with a plane with several issues tying up the gate. I get that that happens from time to time but this has been EVERY flight I've been on for the past 5 years and I fly 3 to 5 times a year. This isn't just United... it's American, it's Delta. It's an issue with the entire industry. I work for UPS and packages on a cargo plane get better service than people do these days. Anymore I HATE flying.

Perfect flight. Smooth flight. Arrived 20 minutes early at destination. Excellent service.

The flights were on time which was great give. It was holiday travel season and there’d been some weather issues. The only complaint and this is every time with United is the terrible seat design. The head rest is not built for comfort and having my neck bent forward for a cross country trip reminded me while I try not to take United flights as a rule.

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

Delays with no explanation. It could have been handled better.

Jill was the flight attendant in first class she was fabulous!! Best flight attendant I have had in years.!! And I fly every other week. Other can learn from her!!

As a first class customer, there was no power the entire flight which limited my ability to work. I find this unacceptable. The first 11 rows on the left side of the plan were out. I was only offered the option to charge my phone which was not the issue because my laptop was out of power. I asked if there was anything that can be done for me, and the answer was, "no". I was not offered any type of compensation for this AA problem which caused me unnecessary stress due to inability to address business issues on an already challenging travel day. Flight attendants tried to reset the power once but that was the extent of their support. Very disappointing for the lack of expected services on a flight. Please contact me with customer focused response to this complaint.

There was no inflight service. Once we landed we were delayed to find a gate for an hour and a half which was 1/2 the total time in the air.

The chicken wrap was tiny ($13 for what looked like a 1/3 of a normal wrap?) and disgusting.

It was good experience this time. The flight was on time.

There was a delay with the plan which cause the flight to leave later and once arrived in Chicago there was another delay and some passengers missed their connecting flights

The gate agent had a really bad attitude and refused to help me get on the standby list. She just handed me a card and said I needed to call a number. I asked her to help with the AA app on my phone and she just shrugged and said she didnt know. After a few phone calls, I eventually just went to a different gate agent on the other side of the terminal and got the help I needed.

Overall, my last three trips on American Airlines have all been either delayed or "rescheduled" due to mechanical issues. At least on delay caused me to miss two possible connecting flights each later than the first. My last option for my last connection required the assistance of the onsite service desk (O'Hare Airport). The wait time for the service desk was such that it jeopardized getting booked on the last connecting flight available for the night. Suffice it to say, my latest experiences with American Airlines have caused me extensive loss of productive business and personal time and can therefore be classified as significantly less than satisfactory.

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

Too many extra fees, uncomfortable, little leg room. Will not recommend this airline.

This airline sucks. They offer low rates then charge you for everything, the app does not work well, the seats are the most uncomfortable. Maintenance issues on the flight, and you still have to sit through their credit card commercials. People are nice enough but does not make up for overall poor experience.

Severe turbulence. Captain never came on to reassure passengers after things settled down.

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

Information on your arrival and departure airports