$172+ Cheap flights from Ontario to St. Louis (STL)
This is the cheapest round-trip flight price found by a Cheapflights user in the last 72 hours by searching for a flight departing on 12/1. Fares are subject to change and may not be available on all flights or dates of travel.
YYZ — STL
Dec 10 — Dec 171
Round-trip
1 adult, Economy
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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
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Cheapest flights from Ontario to St. LouisExplore 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 November 10, 2026.
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 November 10, 2026.
This Kiwi.com deal was found by Cheapflights users on 11/6. 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.
Mon 12/72:25 pm -
2 stops45h 52m
Wed 12/166:20 pm -
1 stop18h 20m
Deal found 11/6![Multiple Airlines logo]()
$341
This Kiwi.com deal was found by Cheapflights users on 11/6. 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.
Tue 12/89:35 am -
2 stops26h 42m
Wed 12/166:20 pm -
1 stop18h 20m
Deal found 11/6![Multiple Airlines logo]()
$351
This Kiwi.com deal was found by Cheapflights users on 11/6. 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.
Mon 12/72:25 pm -
2 stops45h 52m
Tue 12/156:20 pm -
1 stop18h 20m
Deal found 11/6![Multiple Airlines logo]()
$360
This Kiwi.com deal was found by Cheapflights users on 11/6. 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.
Thu 12/37:35 am -
2 stops28h 42m
Wed 12/166:20 pm -
1 stop18h 20m
Deal found 11/6![Multiple Airlines logo]()
$370
This Kiwi.com deal was found by Cheapflights users on 11/6. 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.
Wed 12/910:40 am -
2 stops49h 37m
Tue 12/156:20 pm -
1 stop18h 20m
Deal found 11/6![Multiple Airlines logo]()
$371
This Kiwi.com deal was found by Cheapflights users on 11/6. 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.
Sat 12/56:30 am -
1 stop18h 42m
Wed 12/166:20 pm -
1 stop18h 20m
Deal found 11/6![Multiple Airlines logo]()
$421
This Kiwi.com deal was found by Cheapflights users on 11/6. 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.
Fri 12/46:30 am -
1 stop18h 42m
Fri 12/116:20 pm -
1 stop18h 20m
Deal found 11/6![Multiple Airlines logo]()
$423
This Kiwi.com deal was found by Cheapflights users on 11/6. 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.
Tue 12/112:20 pm -
2 stops23h 50m
Tue 12/86:20 pm -
1 stop20h 04m
Deal found 11/6![Multiple Airlines logo]()
$433
This American Airlines deal was found by Cheapflights users on 11/6. 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.
Tue 12/13:15 pm -
1 stop9h 46m
Tue 12/811:37 am -
1 stop11h 04m
Deal found 11/6![American Airlines logo]()
$434
This United Airlines deal was found by Cheapflights users on 11/8. 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 12/296:15 am -
1 stop16h 07m
Sun 1/39:35 am -
1 stop10h 48m
Deal found 11/8![United Airlines logo]()
$599
This United Airlines deal was found by Cheapflights users on 11/5. 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 12/86:00 am -
1 stop17h 15m
Wed 12/911:00 am -
1 stop9h 56m
Deal found 11/5![United Airlines logo]()
$666
This United Airlines deal was found by Cheapflights users on 11/6. 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 12/236:00 am -
2 stops16h 22m
Sun 1/36:58 pm -
2 stops19h 09m
Deal found 11/6![United Airlines logo]()
$690
Best flights from Ontario to St. LouisDiscover carefully curated flight deals from Ontario to St. Louis that have cost, travel time, and layovers in mind to ensure you get the best travel experience. Data last updated November 10, 2026.
Discover carefully curated flight deals from Ontario to St. Louis that have cost, travel time, and layovers in mind to ensure you get the best travel experience. Data last updated November 10, 2026.
This United Airlines deal was found by Cheapflights users on 11/5. 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 12/82:35 pm -
1 stop9h 24m
Wed 12/95:25 am -
1 stop7h 38m
Deal found 11/5![United Airlines logo]()
$594
This American Airlines deal was found by Cheapflights users on 11/7. 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.
Sat 12/1911:45 am -
1 stop8h 17m
Mon 1/46:00 am -
1 stop10h 40m
Deal found 11/7![American Airlines logo]()
$607
This Delta deal was found by Cheapflights users on 11/7. 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 Delta is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 12/156:00 am -
1 stop10h 54m
Thu 12/312:45 pm -
1 stop8h 12m
Deal found 11/7![Delta logo]()
$649
This Kiwi.com deal was found by Cheapflights users on 11/4. 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 11/151:00 pm -
2 stops25h 31m
Sat 11/211:20 pm -
1 stop28h 53m
Deal found 11/4![Multiple Airlines logo]()
$740
This Air Canada deal was found by Cheapflights users on 11/6. 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.
Sun 11/2211:20 am -
2 stops9h 03m
Thu 11/264:05 pm -
1 stop5h 31m
Deal found 11/6![Air Canada logo]()
$1,106
This United Airlines deal was found by Cheapflights users on 11/8. 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 12/296:15 am -
1 stop16h 07m
Sun 1/39:35 am -
1 stop10h 48m
Deal found 11/8![United Airlines logo]()
$599
This Delta deal was found by Cheapflights users on 11/7. 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 Delta is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 12/167:45 am -
1 stop9h 09m
Sat 12/266:20 am -
1 stop7h 54m
Deal found 11/7![Delta logo]()
$649
This United Airlines deal was found by Cheapflights users on 11/8. 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 12/63:35 pm -
1 stop4h 51m
Sun 12/135:40 pm -
1 stop5h 19m
Deal found 11/8![United Airlines logo]()
$649
This Delta deal was found by Cheapflights users on 11/7. 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 Delta is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 12/157:45 am -
1 stop9h 09m
Sat 12/266:20 am -
1 stop7h 54m
Deal found 11/7![Delta logo]()
$649
This United Airlines deal was found by Cheapflights users on 11/9. 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.
Fri 12/410:30 am -
2 stops8h 46m
Sun 12/66:55 pm -
1 stop4h 04m
Deal found 11/9![United Airlines logo]()
$649
This Delta deal was found by Cheapflights users on 11/7. 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 Delta is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sun 12/136:50 pm -
1 stop15h 02m
Tue 12/296:20 am -
1 stop7h 54m
Deal found 11/7![Delta logo]()
$727
This United Airlines deal was found by Cheapflights users on 11/5. 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 12/86:00 am -
1 stop17h 15m
Wed 12/96:30 am -
2 stops14h 26m
Deal found 11/5![United Airlines logo]()
$666
This United Airlines deal was found by Cheapflights users on 11/9. 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 12/22:10 pm -
Nonstop2h 16m
Fri 12/46:30 am -
1 stop9h 17m
Deal found 11/9![United Airlines logo]()
$683
This United Airlines deal was found by Cheapflights users on 11/6. 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.
Thu 4/86:00 pm -
2 stops21h 18m
Thu 4/156:40 am -
1 stop9h 34m
Deal found 11/6![United Airlines logo]()
$690
This United Airlines deal was found by Cheapflights users on 11/5. 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 2/14:36 pm -
1 stop7h 44m
Sat 2/135:00 am -
1 stop15h 18m
Deal found 11/5![United Airlines logo]()
$698
This Mytrip deal was found by Cheapflights users on 11/6. 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 Mytrip is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sun 11/224:40 pm -
3 stops32h 19m
Thu 11/265:15 pm -
3 stops28h 36m
Deal found 11/6![Multiple Airlines logo]()
$1,357
This Air Canada deal was found by Cheapflights users on 11/5. 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.
Sun 12/205:00 am -
1 stop11h 26m
Sun 12/274:05 pm -
1 stop5h 31m
Deal found 11/5![Air Canada logo]()
$1,489
This Mytrip deal was found by Cheapflights users on 11/5. 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 Mytrip is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sun 12/205:35 pm -
3 stops32h 06m
Sun 12/275:37 pm -
3 stops28h 22m
Deal found 11/5![Multiple Airlines logo]()
$1,812
This United Airlines deal was found by Cheapflights users on 11/5. 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 12/205:00 am -
2 stops8h 26m
Sun 12/275:05 am -
2 stops10h 01m
Deal found 11/5![United Airlines logo]()
$1,078
Last-minute flights from Ontario to St. LouisDiscover last-minute flight deals from Ontario to St. Louis. Data last updated November 10, 2026 and is based on user searches.
Discover last-minute flight deals from Ontario to St. Louis. Data last updated November 10, 2026 and is based on user searches.
This Kiwi.com deal was found by Cheapflights users on 11/6. 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.
Tue 12/112:20 pm -
2 stops23h 50m
Tue 12/86:20 pm -
1 stop20h 04m
Deal found 11/6![Multiple Airlines logo]()
$433
This American Airlines deal was found by Cheapflights users on 11/6. 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.
Tue 12/13:15 pm -
1 stop9h 46m
Tue 12/811:37 am -
1 stop11h 04m
Deal found 11/6![American Airlines logo]()
$434
This Kiwi.com deal was found by Cheapflights users on 11/6. 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.
Thu 12/37:35 am -
2 stops28h 42m
Wed 12/166:20 pm -
1 stop18h 20m
Deal found 11/6![Multiple Airlines logo]()
$370
This Kiwi.com deal was found by Cheapflights users on 11/6. 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.
Fri 12/46:30 am -
1 stop18h 42m
Fri 12/116:20 pm -
1 stop18h 20m
Deal found 11/6![Multiple Airlines logo]()
$423
This Kiwi.com deal was found by Cheapflights users on 11/6. 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.
Sat 12/56:30 am -
1 stop18h 42m
Wed 12/166:20 pm -
1 stop18h 20m
Deal found 11/6![Multiple Airlines logo]()
$421
This Kiwi.com deal was found by Cheapflights users on 11/6. 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.
Mon 12/72:25 pm -
2 stops45h 52m
Wed 12/166:20 pm -
1 stop18h 20m
Deal found 11/6![Multiple Airlines logo]()
$341
This Kiwi.com deal was found by Cheapflights users on 11/6. 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.
Mon 12/72:25 pm -
2 stops45h 52m
Tue 12/156:20 pm -
1 stop18h 20m
Deal found 11/6![Multiple Airlines logo]()
$360
This Kiwi.com deal was found by Cheapflights users on 11/6. 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.
Tue 12/89:35 am -
2 stops26h 42m
Wed 12/166:20 pm -
1 stop18h 20m
Deal found 11/6![Multiple Airlines logo]()
$351
This United Airlines deal was found by Cheapflights users on 11/5. 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 12/86:00 am -
1 stop17h 15m
Wed 12/911:00 am -
1 stop9h 56m
Deal found 11/5![United Airlines logo]()
$666
This Kiwi.com deal was found by Cheapflights users on 11/6. 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.
Wed 12/910:40 am -
2 stops49h 37m
Tue 12/156:20 pm -
1 stop18h 20m
Deal found 11/6![Multiple Airlines logo]()
$371
This United Airlines deal was found by Cheapflights users on 11/6. 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 12/236:00 am -
2 stops16h 22m
Sun 1/36:58 pm -
2 stops19h 09m
Deal found 11/6![United Airlines logo]()
$690
This United Airlines deal was found by Cheapflights users on 11/8. 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 12/296:15 am -
1 stop16h 07m
Sun 1/39:35 am -
1 stop10h 48m
Deal found 11/8![United Airlines logo]()
$599
One-way flights from Ontario to St. LouisSearch for one-way flight options from Ontario to St. Louis. Find affordable one-way fares based on user searches. Data last updated November 10, 2026.
Search for one-way flight options from Ontario to St. Louis. Find affordable one-way fares based on user searches. Data last updated November 10, 2026.
This Kiwi.com deal was found by Cheapflights users on 11/5. 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.
Tue 12/112:20 pm -
2 stops23h 50m
Wed 12/3112:00 am -
Nonstop0h 00m
Deal found 11/5![Multiple Airlines logo]()
$172
This Kiwi.com deal was found by Cheapflights users on 11/6. 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 11/221:00 pm -
2 stops25h 31m
Wed 12/3112:00 am -
Nonstop0h 00m
Deal found 11/6![Multiple Airlines logo]()
$232
This American Airlines deal was found by Cheapflights users on 11/9. 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.
Wed 12/23:22 pm -
1 stop9h 40m
Wed 12/3112:00 am -
Nonstop0h 00m
Deal found 11/9![American Airlines logo]()
$243
This American Airlines deal was found by Cheapflights users on 11/5. 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.
Tue 12/111:45 am -
1 stop9h 05m
Wed 12/3112:00 am -
Nonstop0h 00m
Deal found 11/5![American Airlines logo]()
$249
This Kiwi.com deal was found by Cheapflights users on 11/8. 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.
Tue 12/89:35 am -
2 stops26h 42m
Wed 12/3112:00 am -
Nonstop0h 00m
Deal found 11/8![Multiple Airlines logo]()
$252
This American Airlines deal was found by Cheapflights users on 11/8. 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.
Tue 12/83:22 pm -
1 stop7h 55m
Wed 12/3112:00 am -
Nonstop0h 00m
Deal found 11/8![American Airlines logo]()
$255
This Kiwi.com deal was found by Cheapflights users on 11/7. 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.
Sat 11/216:30 am -
2 stops26h 24m
Wed 12/3112:00 am -
Nonstop0h 00m
Deal found 11/7![Multiple Airlines logo]()
$259
This United Airlines deal was found by Cheapflights users on 11/9. 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.
Thu 12/246:15 am -
1 stop16h 07m
Wed 12/3112:00 am -
Nonstop0h 00m
Deal found 11/9![United Airlines logo]()
$329
This Kiwi.com deal was found by Cheapflights users on 11/9. 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.
Thu 12/248:25 am -
3 stops30h 06m
Wed 12/3112:00 am -
Nonstop0h 00m
Deal found 11/9![Multiple Airlines logo]()
$346
This United Airlines deal was found by Cheapflights users on 11/5. 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 12/206:00 am -
2 stops13h 18m
Wed 12/3112:00 am -
Nonstop0h 00m
Deal found 11/5![United Airlines logo]()
$375
This Kiwi.com deal was found by Cheapflights users on 11/6. 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.
Mon 12/219:15 am -
3 stops50h 38m
Wed 12/3112:00 am -
Nonstop0h 00m
Deal found 11/6![Multiple Airlines logo]()
$376
This United Airlines deal was found by Cheapflights users on 11/6. 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 12/216:00 am -
2 stops16h 22m
Wed 12/3112:00 am -
Nonstop0h 00m
Deal found 11/6![United Airlines logo]()
$380
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 November 10, 2026.
Round-trip from | $341 (Kiwi.com) |
|---|---|
One-way from | $172 (Kiwi.com) |
Popular in | March |
Cheapest in | January |
Average price | $649 |
Good round-trip deal | $640 or less |
Good one-way deal | $444 or less |
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 7,457,451 searches. Data last updated November 10, 2026.
Use the filters below to find and compare flights from Ontario to St. Louis that are best for you.
Fly from
Fly to
Route
Depart
Return
Cheapest round-trip
TorontoSt. Louis
YYZ Toronto Pearson Intl - STL Lambert-St Louis
YYZSTL
Toronto Pearson Intl
Tue 12/1
12:20 pm-11:10 am
2 stops23h 50m
Lambert-St Louis
Wed 12/31
12:00 am-1:00 am
Nonstop0h 00m
$172
TorontoSt. Louis
YYZ Toronto Pearson Intl - STL Lambert-St Louis
YYZSTL
Toronto Pearson Intl
Wed 12/2
3:22 pm-12:02 am
1 stop9h 40m
Lambert-St Louis
Wed 12/31
12:00 am-1:00 am
Nonstop0h 00m
$243
TorontoSt. Louis
YYZ Toronto Pearson Intl - STL Lambert-St Louis
YYZSTL
Toronto Pearson Intl
Tue 12/8
9:35 am-11:17 am
2 stops26h 42m
Lambert-St Louis
Wed 12/31
12:00 am-1:00 am
Nonstop0h 00m
$252
TorontoSt. Louis
YYZ Toronto Pearson Intl - STL Lambert-St Louis
YYZSTL
Toronto Pearson Intl
Tue 12/1
11:45 am-7:27 pm
1 stop8h 42m
Lambert-St Louis
Wed 12/31
12:00 am-1:00 am
Nonstop0h 00m
$259
TorontoSt. Louis
YYZ Toronto Pearson Intl - STL Lambert-St Louis
YYZSTL
Toronto Pearson Intl
Tue 12/29
2:40 pm-12:41 am
1 stop11h 01m
Lambert-St Louis
Wed 12/31
12:00 am-1:00 am
Nonstop0h 00m
$263
TorontoSt. Louis
YYZ Toronto Pearson Intl - STL Lambert-St Louis
YYZSTL
Toronto Pearson Intl
Thu 11/26
6:30 am-12:25 pm
1 stop30h 55m
Lambert-St Louis
Wed 12/31
12:00 am-1:00 am
Nonstop0h 00m
$316
TorontoSt. Louis
YYZ Toronto Pearson Intl - STL Lambert-St Louis
YYZSTL
Toronto Pearson Intl
Mon 12/21
6:30 am-12:41 am
1 stop19h 11m
Lambert-St Louis
Wed 12/31
12:00 am-1:00 am
Nonstop0h 00m
$321
TorontoSt. Louis
YYZ Toronto Pearson Intl - STL Lambert-St Louis
YYZSTL
Toronto Pearson Intl
Wed 12/2
7:20 am-7:26 pm
2 stops13h 06m
Lambert-St Louis
Wed 12/31
12:00 am-1:00 am
Nonstop0h 00m
$325
OttawaSt. Louis
YOW Ottawa - STL Lambert-St Louis
YOWSTL
Ottawa
Thu 12/24
3:10 pm-11:38 pm
2 stops9h 28m
Lambert-St Louis
Wed 12/31
12:00 am-1:00 am
Nonstop0h 00m
$329
OttawaSt. Louis
YOW Ottawa - STL Lambert-St Louis
YOWSTL
Ottawa
Thu 12/24
8:25 am-1:31 pm
3 stops30h 06m
Lambert-St Louis
Wed 12/31
12:00 am-1:00 am
Nonstop0h 00m
$346
Showing 1-10 of 34 resultsSorted by cheapest first
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.
YYZ-STL
YOW-STL
YQT-STL
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
CAON-STL
YYZ-STL
YOW-STL
YQT-STL
What is the cheapest month to book a flight from Region of Ontario to St. Louis?
Currently, January is the cheapest month in which you can book a flight from Region of Ontario to St. Louis (average of $418). Flying from Region of Ontario to St. Louis in November is currently the most expensive (average of $652). 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 November 10, 2026.
One of the essential ways to save on airfare from Region of Ontario to St. Louis is to remain as flexible as possible. Flights that are in the afternoon tend to be the most expensive. A flight at noon could potentially save you up to 20% on airfare.
How much does it cost to fly round-trip from Region of Ontario to St. Louis?
Airfare is below average for this route at the moment.
Region of Ontario to St. Louis flights typically cost between $579 and $848 in December.The cheapest round-trip price found within the last 5 days was $341 on Multiple Airlines (Dec 7-Dec 16).
How far ahead should I book a flight from Region of Ontario to St. Louis?
Booking 65 days in advance of your planned departure date is, on average, the best time to get cheap flights from Region of Ontario to St. Louis. The general trend is that the closer you book to the departure date, the more expensive your flight will be.
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.
Traveling to a place near St. Louis?
Book flights to St. Louis if you plan to visit one of these locationsFairview Heights
O'Fallon
Fenton
Swansea
Eureka
Wentzville
Maryland Heights
Chesterfield
Edwardsville
Glencoe
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Alternative routes for Ontario to St. Louis
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Complete your trip
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Search flights from Ontario to St. Louis by cabin class
Find flights from Ontario to St. Louis, based on your preferred cabin class, be it economy, premium economy, business, or first class.
Ontario and St. Louis flights
Browse other Ontario and St. Louis flight options. Last updated on November 10, 2026.
Popular flight searches
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Other flights to St. Louis
Explore flights to St. Louis departing from other origins. Flights are based on user searches made on Cheapflights and were last updated on November 10, 2026.
Top 2 airlines flying from Ontario to St. Louis
Discover the top 2 airlines 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 7,457,451 searches. Data last updated November 10, 2026.
| Airline | Cheapest | Average | Flexibility | On-time |
|---|---|---|---|---|
| Cheapest$226 | Average$549 | FlexibilityNo cancel fee | On-time69% | |
| Cheapest$256 | Average$480 | FlexibilityNo cancel fee | On-time67% |