$96 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 6/30. 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

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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Best Illinois Flight Deals from Ontario

Cheapest round-trip prices found by our users on KAYAK in the last 72 hours
Chicago
Chicago1 stop$200
Moline
Moline1 stop$289
Peoria
Peoria1 stop$379
Bloomington
Bloomington1 stop$379
St. Louis
St. Louis1 stop$198
Chicago
Chicago1 stop$200
Moline
Moline1 stop$289
Peoria
Peoria1 stop$379
Bloomington
Bloomington1 stop$379
St. Louis
St. Louis1 stop$198

Cheap Flights from Ontario to Illinois

 
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

Sun, Jun 29 - Mon, Jun 30
Frontier Logo
12:59 am - 9:12 amONT-STL
6h 13m1 stop
Frontier Logo
7:29 pm - 11:50 pmSTL-ONT
6h 21m1 stop
$198Frontier
Find Deal
Sun, Jun 29 - Sat, Jul 5
Frontier Logo
12:59 am - 9:12 amONT-STL
6h 13m1 stop
Frontier Logo
7:29 pm - 11:50 pmSTL-ONT
6h 21m1 stop
$200Frontier
Find Deal
Fri, Aug 8 - Fri, Aug 8
American Airlines Logo
12:22 pm - 8:57 pmONT-ORD
6h 35m1 stop
American Airlines Logo
10:10 pm - 9:58 amORD-ONT
13h 48m1 stop
$276American Airlines
Find Deal
Mon, Jun 30 - Tue, Jul 1
Delta Logo
5:08 pm - 12:43 amONT-STL
5h 35m1 stop
Delta Logo
7:15 pm - 10:45 pmSTL-ONT
5h 30m1 stop
$279Delta
Find Deal
Tue, Jul 1 - Fri, Jul 4
Southwest Logo
4:25 pm - 11:55 pmONT-STL
5h 30m1 stop
Southwest Logo
8:40 am - 12:30 pmSTL-ONT
5h 50m1 stop
$288Southwest
Find Deal
Thu, Aug 21 - Sun, Aug 24
American Airlines Logo
2:31 pm - 11:22 pmONT-MLI
6h 51m1 stop
American Airlines Logo
5:24 pm - 12:08 amMLI-ONT
8h 44m1 stop
$289American Airlines
Find Deal
Mon, Jun 30 - Mon, Jun 30
Delta Logo
6:00 am - 1:30 pmONT-STL
5h 30m1 stop
Delta Logo
7:15 pm - 10:45 pmSTL-ONT
5h 30m1 stop
$297Delta
Find Deal
Thu, Aug 14 - Tue, Aug 19
United Airlines Logo
1:34 pm - 9:50 pmONT-STL
6h 16m1 stop
United Airlines Logo
5:30 pm - 10:30 pmSTL-ONT
7h 00m1 stop
$328United Airlines
Find Deal
Thu, Aug 14 - Tue, Aug 19
United Airlines Logo
1:34 pm - 9:50 pmONT-STL
6h 16m1 stop
United Airlines Logo
9:00 am - 5:37 pmSTL-ONT
10h 37m2 stops
$333United Airlines
Find Deal
Tue, Aug 12 - Tue, Aug 19
Southwest Logo
5:45 am - 5:40 pmONT-STL
9h 55m2 stops
Southwest Logo
10:15 am - 5:30 pmSTL-ONT
9h 15m2 stops
$338Southwest
Find Deal
Useful Info

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.

What is the cheapest Ontario to Illinois flight route?

The cheapest price for flight routes found by users searching on KAYAK in the last 2 weeks for round-trip flights from Ontario to Illinois.

The cheapest ticket to Illinois from Ontario found in the last 72 hours was to Chicago, at $227 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 $227.

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 $751 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 November, when tickets cost $225 (return) on average. On the other hand, the most expensive months are March and May, when the average cost of round-trip tickets is $449 and $387 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 Monday, 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 Tuesdays 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 3 weeks before departure. For the absolute cheapest price, our data suggests you should book 20 weeks before departure.


Good to know

Low seasonJanuary
High seasonJuly
Cheapest flight$96
Best time to beat the crowds with an average 6% drop in price.
Most popular time to fly and prices are also 2% lower on average.
Flight from Ontario to Chicago Midway 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.

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

    The cheapest time of day to fly to Illinois is generally at night, when round-trip flights cost $246 on average. Morning departures are around 59% more expensive than evening flights, 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 $531.

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 $194 one-way - $351 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 4280 reviews
8.2Boarding
7.6Entertainment
7.1Food
8.6Crew
8.0Comfort
Airline reviews

Southwest is Southwest. No frills. If you're luck enough to get a happy crew (we did), then it makes for a nicer flight.

10.0 ExcellentMichael, Jun 2025SMF - SEA
Read more Southwest reviews

Southwest is Southwest. No frills. If you're luck enough to get a happy crew (we did), then it makes for a nicer flight.

It was a perfect flight in all aspects! Both legs!

Great flight, 47 passengers on a 180 seat plane. Stewardess was pleasant and cheerful.

I liked the crew member who gave flight instructions on "in case of a problem:. The seats are so small that only a young teenager could sit in middle seat.

Great flight staff. Ease of boarding. Overall, very uneventful and easy trip.

Flight was awfully bumpy and landing was a bit jolting. I was in the restroom when snacks and drinks were served and was not asked if i wanted any. I had to ask for water finally.

Employees were kind and funny, as always! Flight was late but no announcements were made for people with tight connections to help them transition quickly. No service due to turbulence.

I recently flew Southwest from San Jose to Honolulu. I was very impressed with the flight crew, especially the flight attendant in charge of the front of the plane. She came through the aisle at least five times for drinks and water, and two times for snacks. I have not seen such service since I flew first class. Also, for the first time, they gave us the correct baggage claim number, and the luggage came out quickly. I can't wait for Southwest to have assigned seating! I absolutely hate the Cattle Call boarding procedure and the mad dash to get seats and overhead bins. However, the boarding was efficient.

We had a nice flight. Boarding was easy, our seats were comfortable and the on board service was pleasant.

Service was great, boarding and exiting went smoothly, and the flight was very pleasant.

Most aspects were good however if they assign boarding zones they ought to enforce them or why bother? My luggage from SAN-JFK-MAD was lost in NY so I without my main bag for two days upon arrival in Spain. They were helpful in tracking it and eventually delivered it to my hotel. The flub was because of a delay upon arrival in NYC. I had booked 2 1/2 hours between flights but we had to hold on the taxiway for an hour after landing while waiting for a clear gate which likely caused the baggage error.

Excellent flight, the planes were newer, they did a nice job with boarding, great service overall.

It would be nice if was given wires ear buds. Overall was a good experience was able to sleep on the plane

737-800 in first class was pretty dumpy. Seat had an uncomfortable angle, storage under the seat was blocked so even my very modest backpack didn't fit, power outlet was flaky. Weird tiny seat pockets that couldn't hold a gallon ziploc bag, emesis bag missing, etc. etc. No in-flight service due to turbulence. Crew was excellent, boarding was smooth despite a full flight.

Delta flight was on time, seats were comfortable, and crew was nice.

Thank you for not flipping the plane on the run way. You guys get a 5 star rating for the flight!!!

Boarding is, as it always is… horrible. Gate lice. Slow moving zones. Too many people with carry ons

It was terrible, if they ran flights on time it would make a big difference.

Delta seems to be improving in many areas, except they are super bad with the food available. Bring back normal food service on long flights.

I actually received a notification from kayak on email but not one by text from Delta when my departure gait changed and I almost missed my flight

It was fine, definitely older planes with no charging or anything. There’s no entertainment set up on board, but it is nice that they allow you to access the in flight entertainment from your phone without having to pay for the Wi-Fi and they do offer free texting.

I liked that the flight was nonstop from ORD to CIU for $200 round trip.

The schedule to Moline changed 5 times. The gate changed 6 times. That is a pathetic way to run an airline. No wonder that no one in our company flies on United Express to or from Moline. Changes happen most of the time. I learned my lesson on this trip…never again!

While the staff was pleasant and helpful, the following observations are for your awareness. There was some delay on the tarmac on take off and landing. The paid lunch/food offerings were limited. Entertainment was only available on WiFi at a cost.

The first flight was better in terms of the aircraft.

Smooth flight. Boarding was chaotic. Could not hear the gate agent over the intercom. People were lined up in the wrong lines. Groups one and two were told to board through line one and group 3 through line 2. All very confusing. Once in the air, the flight was smooth. There was no entertainment option on this aircraft, even though it was a larger aircraft.

Overall poor for me I paid extra for seats with leg room and my regional flights exit row seats have less leg room then the others that's money that could have been saved and on my final flight home the flights air was not operating it was unbearably hot in the cabin I will be contacting United and filing a DOT complaint

There's just no way to sit fully upright and comfortably in these seats. There needs to be 2 more inches of room, and that's not something that only one person on the flight needs - the whole flight needs 2 more inches of room. If that means you sell 6 less seats, so be it. It's too close for anyone. Forcing people to pay for "premium" economy just to get "barely enough space to breathe" isn't really an answer to that.

The crew were very nice. The Chocolate is good and v there’s no entertainment. Thanks

The crew were very nice. I would have appreciated a pillow for comfort. I had a special meal that was sloppy, but the salad was great. Thanks

The chair cushions may need an upgrade. I have been noticing they are so worn out, thin so you’d sit in a dip 😄. Other than that, all was an enjoyable trip. Thanks AA!

Most miserable flight ever. We waited almost 2 hours on the runway because the flight was oversold. American offered $1200 credit. Then there was some nonsense about weight distribution. Ridiculous. No food for 8 plus hours on the flight. I will be writing a letter.

The flight was 2 hour delayed, otherwise everything was excellent. The delay was due to the hourly limit requirement so given that as a reason, I'm happy with the flight!

Not sure the logic of the boarding in Groups. I was loaded first on the aisle. Then the guy in the middle. Then the guy by the window. Constantly holding up the other people boarding behind them with us blocking the aisle and this happened in most of the other rows

To start, I’d like to say that every American Airline personnel I interacted with on the ground, especially flight crew, was very friendly and did their best to help me out. Despite this, however, my experience with the airline was an entire mess. The 7:19 PM flight was heavily delayed due to weather, and pushed to 10:30 AM the next morning. Because of this, I had to spend the night inside of the airport. At some point later in the night, I got an email saying that the flight had been canceled. I called the support number, and the representative on the other line told me that the flight was still on and that I didn’t need to rebook. The next morning, no one came to the gate to open the door for the crew until almost 11 AM. By this time the flight crew had been waiting for over an hour, and they had called management to get someone to open the door for them multiple times. Around 11:30, the gate screen had changed to a different flight. I ended up buying a last minute ticket with Southwest airline just to get to Chicago, because the next flight with American wasn’t until 7:19 pm that day. Now, earlier that morning my suitcase had been sent ahead of me to ORD. I went to baggage claim to ask them if I could have my suitcase forwarded to where I was staying. The representative at SDF baggage claim said they could and put the claim in for me. As I was going back through TSA, I got an email that the airline had found my suitcase, but the next step was to send it BACK to SDF. I called the airline support number again, and I made it clear that my suitcase needed to stay in Chicago and to not come back to SDF. The representative told me that they would hold my suitcase at ORD and that it wasn’t going to be forwarded anywhere. Once I got there, I found that they had loaded my suitcase onto a plane to send it back to SDF. Thankfully, I had gotten to the baggage claim counter in time for them to put in a request to bring my suitcase back up. My refund with the airline is processing already, but because of this entire experience and miscommunication at every turn of the way, I will not book with American Airlines in the future.

The plane was late and then sat on the runway for almost 45 minutes before taking off.

Crew professional. Easy bag drop off. On time. Good entertainment.

Everything was great. Boarding, early departure, early arrival, and deplaning were smooth. Smooth flight.

Per usual, flight status, staff courtesy and professionalism were excellent

Everything was on time, we arrived early, everything worked well.

Cancelled flight after I arrived at airport after 75 min drive and parking. Next flight was 4 days in the future. Had to scramble and buy a much more expensive flight on another carrier.

I liked the turn-style feature at gate 209B at LAX. Very efficient process. The gate staff also made several, clearly directed announcements so I felt very informed.

The crew was delayed because they came on another flight that was delayed due to weather 10pm flight left at 1.30 am The airline made no effort to align alternate crew

The seats were awful, hard plastic covered in sheet vinyl. The airline tries to scam you into paying extra to get seat together when the flight wasn’t full. They were going to separate a family with young children but my wife who had a row to herself gave up her seat so the young mom could be with her young boys. I’m never giving this airline my money again.

It was a short flight so no food or entertainment….

Frontier had yet another flight cancellation. Have never made a complete round trip with this airline without at least one leg getting cancelled. Miserable flights - dirty, uncomfortable planes that apparently always have issues since I've had multiple delays and cancellations with them.

Flight was delayed 3 times, would have been nice to have received text message instead of email notifications. Frontier app wasn’t even updated accordingly, no gate number disclosed. No agent at front desk of gate to inform of delay. Very confused and left if the dark

The flight itself was ok and the pilot was very communicative. However, our flight was delayed for almost 3 hours, the gate was changed 3 times and there was no communication as we were waiting. The flight staff was overall a little crabby...I understand as they probably had a long day but we all did.

They changed the timing , first delayed by 4 hours then went back to 40 mins late, we had to run back to airport to not miss our flight. This is ridiculous

No frills for sure. No gate announcements about flight delay, not even water to drink on the flight.

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