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Cheap flights from St. Louis to Ontario from C$ 149

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 25/1. Fares are subject to change and may not be available on all flights or dates of travel.
STL — YYZ
11 Jan — 18 Jan1
1 adult
1 adult, Economy, 0 bags

Cheap flight deals from St. Louis to Ontario

Enter your travel dates to find the best prices.

Cheapest flights from St. Louis to Ontario
Explore the most affordable flight options available from St. Louis to Ontario. Find the lowest fares from popular airlines and budget airlines, with prices last updated on 12 December 2025.

Thu 25/126:00 a.m.STL - YYZ
1 stop3h 56mAmerican Airlines
Tue 30/121:12 p.m.YYZ - STL
1 stop11h 32mAmerican Airlines
Deal found 11/12C$ 681
Thu 25/128:05 a.m.STL - YYZ
2 stops9h 52mUnited Airlines
Tue 30/125:30 p.m.YYZ - STL
1 stop5h 13mUnited Airlines
Deal found 10/12C$ 694
Tue 30/126:35 p.m.STL - YYZ
1 stop4h 24mAir Canada
Fri 2/16:45 p.m.YYZ - STL
1 stop4h 58mAir Canada
Deal found 11/12C$ 785
Thu 25/123:10 p.m.STL - YYZ
2 stops7h 36mAir Canada
Tue 30/124:50 p.m.YYZ - STL
1 stop5h 53mAir Canada
Deal found 11/12C$ 798
Fri 19/128:37 p.m.STL - YYZ
1 stop14h 06mMultiple Airlines
Sun 4/18:20 p.m.YYZ - STL
1 stop14h 25mMultiple Airlines
Deal found 9/12C$ 811
Wed 31/126:00 a.m.STL - YUL
1 stop17h 40mMultiple Airlines
Mon 5/14:35 p.m.YUL - STL
1 stop30h 58mMultiple Airlines
Deal found 11/12C$ 816
Tue 30/126:35 p.m.STL - YYZ
1 stop4h 24mUnited Airlines
Thu 1/19:00 a.m.YYZ - STL
2 stops14h 22mUnited Airlines
Deal found 10/12C$ 844
Tue 30/1210:48 a.m.STL - YUL
2 stops36h 42mMultiple Airlines
Mon 5/14:35 p.m.YUL - STL
1 stop30h 58mMultiple Airlines
Deal found 11/12C$ 847
Sun 14/123:30 p.m.STL - YYZ
1 stop19h 13mMultiple Airlines
Tue 16/128:30 p.m.YYZ - STL
2 stops38h 10mMultiple Airlines
Deal found 10/12C$ 885
Tue 23/1211:51 a.m.STL - YYZ
1 stop22h 52mMultiple Airlines
Thu 25/127:40 a.m.YYZ - STL
2 stops15h 53mMultiple Airlines
Deal found 10/12C$ 907
Tue 23/126:35 p.m.STL - YYZ
1 stop4h 24mUnited Airlines
Thu 25/126:40 p.m.YYZ - STL
1 stop6h 03mUnited Airlines
Deal found 10/12C$ 910
Mon 15/1210:47 a.m.STL - YYZ
2 stops12h 38mMultiple Airlines
Sat 3/17:10 a.m.YYZ - STL
1 stop16h 23mMultiple Airlines
Deal found 10/12C$ 938

Find flight deals from St. Louis to Ontario

Keep the following information in mind while searching for St. Louis to Ontario flight deals. Data was last updated 12 December 2025.

Round-trip from

C$ 356

One-way from

C$ 149

Popular in

November

Cheapest in

April

Average price

C$ 679
8/1-15/1
  • 8/1-15/1
  • 3 total stops
  • 35h 24m total
  • St. Louis to Ontario
Search Deals
25/1
  • 25/1
  • 2 total stops
  • 25h 29m total
  • St. Louis to Ontario
Search Deals
Highest demand for flights based on searches. 14% potential increase in price (C$ 159 potential increase over avg. RT price).
Search Deals
Cheapest flight prices on average. 3% potential price decrease (C$ 35 potential savings vs. average RT price).
Search Deals
Average for round-trip flights in December 2025
Search Deals

Cheapflights Fare Finder

 
Customize your flight search to find flights from St. Louis to Ontario 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 629,999 searches. Data last updated 12 December 2025.
Use the filters below to find and compare flights from St. Louis to Ontario that are best for you.

Fly from

St. Louis

Fly to

Ontario

Route

Depart

Return

Price

St. LouisToronto

STL - YYZ

STLYYZ

Lambert-St Louis

Sun 25/1

5:42 p.m.-8:11 p.m.

2 stops25h 29m

Toronto Pearson Intl

Sun 1/2

8:00 p.m.-8:50 p.m.

1 stop25h 50m

C$ 385

St. LouisToronto

STL - YYZ

STLYYZ

Lambert-St Louis

Sat 14/2

6:35 p.m.-10:56 a.m.

1 stop15h 21m

Toronto Pearson Intl

Sat 21/2

6:00 a.m.-2:45 p.m.

1 stop9h 45m

C$ 484

St. LouisToronto

STL - YYZ

STLYYZ

Lambert-St Louis

Fri 27/3

9:50 a.m.-9:09 p.m.

2 stops10h 19m

Toronto Pearson Intl

Mon 30/3

7:10 a.m.-11:19 p.m.

1 stop17h 09m

C$ 579

St. LouisToronto

STL - YYZ

STLYYZ

Lambert-St Louis

Mon 16/3

4:05 p.m.-7:06 p.m.

Nonstop2h 01m

Toronto Pearson Intl

Fri 20/3

2:00 p.m.-3:29 p.m.

Nonstop2h 29m

C$ 647

St. LouisToronto

STL - YYZ

STLYYZ

Lambert-St Louis

Fri 6/3

4:05 p.m.-7:06 p.m.

Nonstop2h 01m

Toronto Pearson Intl

Sun 8/3

2:00 p.m.-3:29 p.m.

Nonstop2h 29m

C$ 647

St. LouisToronto

STL - YYZ

STLYYZ

Lambert-St Louis

Fri 27/3

4:05 p.m.-7:06 p.m.

Nonstop2h 01m

Toronto Pearson Intl

Sun 29/3

2:10 p.m.-3:24 p.m.

Nonstop2h 14m

C$ 647

St. LouisToronto

STL - YYZ

STLYYZ

Lambert-St Louis

Sun 25/1

4:05 p.m.-7:06 p.m.

Nonstop2h 01m

Toronto Pearson Intl

Sun 1/2

2:00 p.m.-3:29 p.m.

Nonstop2h 29m

C$ 647

St. LouisToronto

STL - YYZ

STLYYZ

Lambert-St Louis

Thu 8/1

4:05 p.m.-7:06 p.m.

Nonstop2h 01m

Toronto Pearson Intl

Thu 15/1

2:00 p.m.-3:29 p.m.

Nonstop2h 29m

C$ 647

St. LouisToronto

STL - YYZ

STLYYZ

Lambert-St Louis

Sat 14/2

4:05 p.m.-7:06 p.m.

Nonstop2h 01m

Toronto Pearson Intl

Sat 21/2

2:00 p.m.-3:29 p.m.

Nonstop2h 29m

C$ 647

St. LouisMontreal

STL - YUL

STLYUL

Lambert-St Louis

Thu 26/2

6:00 a.m.-3:05 p.m.

1 stop8h 05m

Montreal Pierre Elliott Trudeau Intl

Mon 2/3

3:55 p.m.-9:29 a.m.

1 stop18h 34m

C$ 739

Flights are sorted by cheapest round-trip flights first.

Deals found on 11/12

Showing 1-10 of 33 results
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Best time to book a flight from St. Louis to Ontario

Have a flexible travel schedule? Discover the best time to fly to Ontario from St. Louis 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 St. Louis to Ontario

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

Currently, June is the cheapest month in which you can book a flight from St. Louis to Region of Ontario (average of C$ 247). Flying from St. Louis to Region of Ontario in October is currently the most expensive (average of C$ 712). 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 STL to ON?

Find hourly flight availability from St. Louis to Ontario. Discover flight options and departure times throughout the day, allowing you to choose a departure time that suits your schedule. Data last updated 12 December 2025.

When flying from St. Louis to Region of Ontario, the time of day you decide to fly out makes little to no difference towards the overall price you’ll pay on tickets.

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

Reviews of airlines servicing Ontario

Get insights into the airlines that provide service to Ontario. Read reviews, discover amenities, and learn about the overall travel experience offered by airlines. Use this information to make informed decisions when choosing an airline for your flight to Ontario. Reviews last updated 12 December 2025.
See what other customers who have flown with Air Canada from St. Louis to Ontario have to say. Users can see the overall rating for each airline as well as how each is rated in terms of entertainment options, comfort, food, crew/service, and boarding process.
Air Canada
7.1
Good
10,516 reviews
Check prices

Comfort

7.1

Boarding

7.3

Food

6.3

Crew

7.8

Entertainment

6.8

Overall

7.1

Reviews

1 / 20
2.0
Mediocre

Shawna,Sep 2025

DCA - YYZ

Business class cabin was *freezing*. Landing was so hard it injured my back - no apology or explanation given
Air Canada
7.1
Good
10,516 reviews
Air Canada
7.1
Good
10,516 reviews
Check prices

Comfort

7.1

Boarding

7.3

Food

6.3

Crew

7.8

Entertainment

6.8

Overall

7.1

Reviews

1 / 20
2.0
Mediocre

Shawna,Sep 2025

DCA - YYZ

Business class cabin was *freezing*. Landing was so hard it injured my back - no apology or explanation given

Related info for your journey

Find useful and relevant information for your journey from St. Louis to Ontario. 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 from for flights from St. Louis to Ontario?

    If you book a flight to Ontario from St. Louis, you will be flying from Lambert-St Louis, which is the city’s only airport. Lambert-St Louis (STL) is located 20.4 km from the centre of St. Louis.

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

    Departing from St. Louis to Region of Ontario will take you 4h 15m. St. Louis and Region of Ontario are separated by a distance of 908 km. Both multi-stop and direct flights can be found to your destination and back.

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

    The most popular flight routes from St. Louis to Region of Ontario are Lambert-St Louis - Toronto Pearson Intl, Lambert-St Louis - Montreal Pierre Elliott Trudeau Intl and Lambert-St Louis - London.

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

    Before booking your flight to Region of Ontario from St. Louis, check out the most reliable airlines to get you to your destination on time: Air Canada (94%), Jazz (94%), United Airlines( 94%).

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

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

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

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

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

    Yes. Cheapflights offers flight deals from St. Louis to Ontario 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 St. Louis to Region of Ontario?

    Currently, June is the cheapest month in which you can book a flight from St. Louis to Region of Ontario (average of C$ 247). Flying from St. Louis to Region of Ontario in October is currently the most expensive (average of C$ 712). 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

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Alternative routes for St. Louis to Ontario

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

Top airline flying from St. Louis to Ontario

Discover the top airline that operate flights from St. Louis to Ontario. 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 629,999 searches. Data last updated 12 December 2025.
AirlineCheapestAverageFlexibilityOn-time
Air CanadaCheapestC$ 301AverageC$ 643FlexibilityNo cancel feeOn-time67%
Search Air Canada flights

Fly with Cheapflights

Find the best flight deals on Cheapflights, where travelers can enjoy low prices and a wide availability of flights to their desired destinations.

How does Cheapflights help users find flights from St. Louis to Ontario?

Cheapflights helps you search for flights from St. Louis to Ontario via 900+ travel sites so you don’t have to. After performing a flight search, users can also filter their flight selection by filtering for price, number of stops, airlines, and so on.

Why should you use Cheapflights to find cheap flight tickets from St. Louis to Ontario?

By finding flights from multiple airlines and providers at completely no cost, Cheapflights helps millions of users like you annually find the best flights to Ontario from St. Louis.

Can Cheapflights find flights from St. Louis to Ontario with no change fees?

Certainly. Search results for flights to Ontario from St. Louis shown to you on Cheapflights can be narrowed down with different useful search filters, which includes flexible booking options.

Can Cheapflights notify me if prices for flights from St. Louis to Ontario become cheaper?

Yes! Start tracking prices for St. Louis to Ontario flights today and get alerted whenever prices for these flights change. To access this feature, click the bell icon next to the flight deals above, which will prompt you for a valid email address to receive your alerts.

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