HomeSearch by dateVacation packagesHotelsFlight dealsCar rentalTravel tips & news
St. Louis

$135+ Cheap flights from Ontario to St. Louis (STL)

This is the cheapest one-way flight price found by a Cheapflights user in the last 72 hours by searching for a flight departing on 1/15. Fares are subject to change and may not be available on all flights or dates of travel.
YYZ — STL
Jan 14 — Jan 211
Wed 1/14
Wed 1/21
1 adult, Economy
We work with more than 300 partners to bring you better travel deals

Find cheap flights from Ontario to St. Louis with Cheapflights

1. Tell us where you want to go

Enter your travel information like dates, passengers, trip type (one-way or round trip), and preferred cabin class then click “Find deals”

2. Select your favorite providers

We find the providers serving your travel needs. Choose up to four travel providers to compare side-by-side for flights, hotels, or car rentals.

3. Compare prices and book

Review each provider’s pricing and select the best option for you! Book through your favorite provider’s website for a seamless experience.

Cheap flight deals from Ontario to St. Louis

Cheapest flights from Ontario to St. Louis
Explore the most affordable flight options available from Ontario to St. Louis. Find the lowest fares from popular airlines and budget airlines, with prices last updated on December 15, 2025.

This United Airlines deal was found by Cheapflights users on 12/14. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure United Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 12/305:30 pmYYZ - STL
1 stop6h 13mUnited Airlines
Sat 1/36:35 pmSTL - YYZ
1 stop4h 24mUnited Airlines
Deal found 12/14$497
This United Airlines deal was found by Cheapflights users on 12/13. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure United Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Mon 12/297:27 pmYOW - STL
2 stops18h 00mUnited Airlines
Tue 12/306:35 pmSTL - YOW
2 stops17h 57mUnited Airlines
Deal found 12/13$517
This Air Canada deal was found by Cheapflights users on 12/13. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Air Canada is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Mon 12/299:15 amYOW - STL
1 stop7h 14mAir Canada
Tue 12/303:10 pmSTL - YOW
1 stop5h 08mAir Canada
Deal found 12/13$530
This United Airlines deal was found by Cheapflights users on 12/14. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure United Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sun 12/286:50 amYYZ - STL
1 stop6h 37mUnited Airlines
Sat 1/36:35 pmSTL - YYZ
1 stop4h 24mUnited Airlines
Deal found 12/14$534
This Air Canada deal was found by Cheapflights users on 12/14. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Air Canada is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 12/306:45 pmYYZ - STL
1 stop4h 58mAir Canada
Sat 1/36:35 pmSTL - YYZ
1 stop4h 24mAir Canada
Deal found 12/14$543
This United Airlines deal was found by Cheapflights users on 12/13. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure United Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 12/249:00 amYYZ - STL
1 stop9h 54mUnited Airlines
Mon 12/296:35 pmSTL - YYZ
1 stop4h 24mUnited Airlines
Deal found 12/13$596
This United Airlines deal was found by Cheapflights users on 12/13. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure United Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 12/2010:00 amYYZ - STL
2 stops13h 43mUnited Airlines
Sat 1/33:10 pmSTL - YYZ
1 stop7h 09mUnited Airlines
Deal found 12/13$615
This American Airlines deal was found by Cheapflights users on 12/14. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure American Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 12/263:59 pmYUL - STL
1 stop5h 52mAmerican Airlines
Fri 1/25:30 amSTL - YUL
1 stop5h 50mAmerican Airlines
Deal found 12/14$676
This Air Canada deal was found by Cheapflights users on 12/13. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Air Canada is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 12/252:00 pmYYZ - STL
Nonstop2h 29mAir Canada
Mon 12/296:35 pmSTL - YYZ
1 stop4h 24mAir Canada
Deal found 12/13$689
This Kiwi.com deal was found by Cheapflights users on 12/14. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sun 12/144:35 pmYUL - STL
1 stop17h 24mMultiple Airlines
Wed 12/173:30 pmSTL - YUL
1 stop8h 00mMultiple Airlines
Deal found 12/14$716
This Air Canada deal was found by Cheapflights users on 12/12. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Air Canada is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 12/2610:10 amYUL - STL
1 stop6h 19mAir Canada
Fri 1/28:05 amSTL - YUL
2 stops10h 17mAir Canada
Deal found 12/12$730
This Air Canada deal was found by Cheapflights users on 12/14. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Air Canada is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 12/242:00 pmYYZ - STL
Nonstop2h 29mAir Canada
Mon 12/296:35 pmSTL - YYZ
1 stop4h 24mAir Canada
Deal found 12/14$752

Find flight deals from Ontario to St. Louis

Keep the following information in mind while searching for Ontario to St. Louis flight deals. Data was last updated December 15, 2025.

Round-trip from

$215
(Kiwi.com)

One-way from

$135
(Kiwi.com)

Popular in

September

Cheapest in

June

Average price

$518

Good round-trip deal

$542 or less
From Ontario to Lambert-St Louis
Search Deals
One-way flight from Ontario to Lambert-St Louis
Search Deals
High demand for flights, 1% potential price rise
Search Deals
Cheapest flight prices on average. 1% potential price decrease ($7 potential savings vs. average RT price).
Search Deals
Average for round-trip flights in December 2025
Search Deals
Price to beat on a round-trip flight from Ontario to Lambert-St Louis.
Search Deals

Cheapflights Fare Finder

 
Customize your flight search to find flights from Ontario to St. Louis that fit within your specific budget. Explore options based on user searches and filter the results based on your desired price range. Find flights that match your budget for a cost-effective journey. Over the last 7 days, Cheapflights users made 2,558,603 searches. Data last updated December 15, 2025.
Use the filters below to find and compare flights from Ontario to St. Louis that are best for you.

Fly from

Ontario

Fly to

St. Louis

Route

Depart

Return

Price

TorontoSt. Louis

YYZ - STL

YYZSTL

Toronto Pearson Intl

Sun 1/11

7:10 am-8:05 am

1 stop25h 55m

Lambert-St Louis

Sat 1/17

3:43 pm-6:20 am

2 stops37h 37m

$276

MontrealSt. Louis

YUL - STL

YULSTL

Montreal Pierre Elliott Trudeau Intl

Sun 1/25

4:35 pm-9:21 am

1 stop17h 46m

Lambert-St Louis

Tue 2/3

5:42 pm-5:00 pm

2 stops22h 18m

$295

OttawaSt. Louis

YOW - STL

YOWSTL

Ottawa

Thu 1/8

5:11 pm-10:58 pm

1 stop6h 47m

Lambert-St Louis

Mon 1/12

3:11 pm-9:18 pm

1 stop5h 07m

$304

TorontoSt. Louis

YYZ - STL

YYZSTL

Toronto Pearson Intl

Sun 1/11

7:10 am-8:05 am

1 stop25h 55m

Lambert-St Louis

Thu 2/5

10:01 pm-7:36 pm

2 stops20h 35m

$307

TorontoSt. Louis

YYZ - STL

YYZSTL

Toronto Pearson Intl

Mon 1/5

5:15 pm-10:33 pm

1 stop30h 18m

Lambert-St Louis

Sat 1/10

7:43 pm-2:05 pm

2 stops17h 22m

$331

OttawaSt. Louis

YOW - STL

YOWSTL

Ottawa

Thu 1/8

6:00 am-2:30 pm

2 stops9h 30m

Lambert-St Louis

Mon 1/12

8:05 am-7:18 pm

2 stops10h 13m

$364

TorontoSt. Louis

YYZ - STL

YYZSTL

Toronto Pearson Intl

Tue 2/24

6:00 am-1:54 pm

1 stop8h 54m

Lambert-St Louis

Sat 2/28

1:33 pm-10:55 pm

1 stop8h 22m

$376

TorontoSt. Louis

YYZ - STL

YYZSTL

Toronto Pearson Intl

Tue 2/24

2:00 pm-3:29 pm

Nonstop2h 29m

Lambert-St Louis

Sat 2/28

4:05 pm-7:06 pm

Nonstop2h 01m

$392

TorontoSt. Louis

YYZ - STL

YYZSTL

Toronto Pearson Intl

Thu 1/15

2:00 pm-3:29 pm

Nonstop2h 29m

Lambert-St Louis

Sun 1/18

4:05 pm-7:06 pm

Nonstop2h 01m

$392

TorontoSt. Louis

YYZ - STL

YYZSTL

Toronto Pearson Intl

Thu 2/12

10:51 am-9:05 pm

1 stop11h 14m

Lambert-St Louis

Thu 2/26

7:41 am-5:49 pm

2 stops9h 08m

$397

Flights are sorted by cheapest round-trip flights first.

Deals found on 12/14

Showing 1-10 of 31 results
1
2
3
4

Best time to book a flight from Ontario to St. Louis

Have a flexible travel schedule? Discover the best time to fly to St. Louis from Ontario with our price prediction graph.
Estimated round-trip price
Rates are based on past data. Find the cheapest month and day to book your flight based on your travel requirements, then search for cheap deals.

Cheapflights Insights

Everything you need to know about your flight from Ontario to St. Louis

What is the cheapest month to book a flight from Region of Ontario to St. Louis?

Currently, December is the cheapest month in which you can book a flight from Region of Ontario to St. Louis (average of $254). Flying from Region of Ontario to St. Louis in April is currently the most expensive (average of $373). There are several factors that can impact the price of a flight, so comparing airlines, departure airports and flight times can provide users with more options.

What is the cheapest time of day to fly from ON to STL?

Find hourly flight availability from Ontario to St. Louis. Discover flight options and departure times throughout the day, allowing you to choose a departure time that suits your schedule. Data last updated December 15, 2025.

Regardless of the time of day you decide to fly, the ticket price will remain around the same. Book flights from Region of Ontario to St. Louis as you normally would.

How much does it cost to fly round-trip from Region of Ontario to St. Louis?

Related info for your journey

Find useful and relevant information for your journey from Ontario to St. Louis. Access travel guides, tips, and recommendations to enhance your travel experience. Get information about local attractions, weather, transportation options, and more.

  • What airport do you fly into for flights to St. Louis from Ontario?

    Located just 12.7 mi from the city center, Lambert-St Louis (STL) is the airport most travelers will use when flying to St. Louis from Ontario.

  • How long is the flight from Region of Ontario to St. Louis?

    Departing from Region of Ontario to St. Louis will take you 6h 47m. The distance between Region of Ontario and St. Louis is about 878 mi. When browsing for deals, the options you’ll see will be for both nonstop flights and flights with stops.

  • What are the cheapest airlines to fly from Region of Ontario to St. Louis one-way?

    $187 is the cheapest one-way deal found within the past few days, from Air Canada. You may also be able to find cheap deals on United Airlines and American Airlines, with prices starting from $188 and $219, respectively.

  • What are the most popular routes from Region of Ontario to St. Louis?

    While some choose either Montreal Pierre Elliott Trudeau Intl - Lambert-St Louis or Ottawa - Lambert-St Louis, Toronto Pearson Intl - Lambert-St Louis is the most popular route from Region of Ontario to St. Louis.

  • What are the most reliable airlines from Region of Ontario to St. Louis?

    Looking for the most reliable airlines to get you to your destination on time? Our data shows these are most likely to get you from Region of Ontario to St. Louis on time: United Airlines (84%), Air Canada (81%), Jazz (81%).

  • What are the cheapest flights from Region of Ontario to St. Louis?

    The cheapest flight price from Region of Ontario to St. Louis is $368. On average you can expect to pay $1,089. The most popular route, (Toronto Pearson Intl - Lambert-St Louis), can usually be booked for $215.

  • Can I find deals for flights from Ontario to St. Louis that include hotel bookings?

    Yes. In addition to deals on Ontario to St. Louis flights, Cheapflights offers vacation packages that include both flights and hotel.

  • How can I find direct flights from Ontario to St. Louis?

    After entering your origin and destination, apply the non-stop filter on the search result page to find direct flights from Ontario to St. Louis.

  • Can I find deals for business class flights from Ontario to St. Louis?

    Yes. Cheapflights offers flight deals from Ontario to St. Louis by cabin class. In addition to browsing deals, you can also filter by cabin class on the search results page after making a search.

  • What is the cheapest month to book a flight from Region of Ontario to St. Louis?

    Currently, December is the cheapest month in which you can book a flight from Region of Ontario to St. Louis (average of $254). Flying from Region of Ontario to St. Louis in April is currently the most expensive (average of $373). There are several factors that can impact the price of a flight, so comparing airlines, departure airports and flight times can provide users with more options.

See more FAQs

Traveling to a place near St. Louis?

Book flights to St. Louis if you plan to visit one of these locations
Edwardsville
O'Fallon
Fairview Heights
Maryland Heights
Collinsville
Swansea
Eureka
Glencoe
St. Peters
Chesterfield
Alton
Farmington
Festus

Browse thousands of different options on Cheapflights for your next trip

Toggle through the tabs below to find thousands of options on Cheapflights for your next trip.

Alternative routes for Ontario to St. Louis

See prices for flight routes from nearby airports that may be better suited for you.
Pierre Elliott Trudeau Intl to Kansas City flights
Pearson Intl to Kansas City flights
Pearson Intl to St. Louis flights
Pierre Elliott Trudeau Intl to St. Louis flights
Vancouver Intl to Kansas City flights
Charlottetown to St. Louis flights
Vancouver Intl to St. Louis flights
Edmonton to Kansas City flights
Ottawa to Kansas City flights
Calgary to Kansas City flights
Calgary to St. Louis flights
Halifax to St. Louis flights
Kelowna to Kansas City flights
Halifax to Kansas City flights
Ottawa to St. Louis flights
Vancouver Intl to Springfield flights
Pearson Intl to Springfield flights
Pearson Intl to Joplin flights
Winnipeg to St. Louis flights
Winnipeg to Kansas City flights
Saskatoon to Kansas City flights
Victoria to St. Louis flights
Edmonton to St. Louis flights

Top airline flying from Ontario to St. Louis

Discover the top airline that operate flights from Ontario to St. Louis. Compare their services, reliability, and customer satisfaction ratings to choose the airline that best suits your travel preferences and needs. Over the last 7 days, Cheapflights users made 2,558,603 searches. Data last updated December 15, 2025.
AirlineCheapestAverageFlexibilityOn-time
Air CanadaCheapest$324Average$561FlexibilityNo cancel feeOn-time67%

100% Free

Cheapflights is completely free to use, so you can start saving the moment you arrive.

Book with Flexibility

Our users can plan ahead with confidence and find flights with no change fees

Travel Smart

Millions of people come to us for their flight needs every year. We help make travel planning easy by providing useful insights and data-driven graphs that can inform your decisions.
Site
©2025 Cheapflights