$67+ Cheap flights from Ontario to St. Louis (ONT - 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 12/8. Fares are subject to change and may not be available on all flights or dates of travel.
ONT — STL
Nov 29 — Dec 61
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
Cheapest
Best
Last-minute
One-way
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 October 30, 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 October 30, 2026.
This Mytrip deal was found by Cheapflights users on 10/27. 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.
Fri 12/411:30 am -
1 stop21h 27m
Mon 12/77:54 pm -
1 stop16h 51m
Deal found 10/27![Frontier logo]()
$138
This Mytrip deal was found by Cheapflights users on 10/27. 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.
Fri 12/1111:30 am -
1 stop21h 27m
Mon 12/147:54 pm -
1 stop6h 26m
Deal found 10/27![Frontier logo]()
$141
This Cheapflightsfares deal was found by Cheapflights users on 10/28. 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 Cheapflightsfares is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 12/186:30 am -
1 stop6h 56m
Mon 1/116:20 pm -
1 stop7h 55m
Deal found 10/28![Frontier logo]()
$159
This Trip.com deal was found by Cheapflights users on 10/29. 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 Trip.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sun 12/66:00 am -
1 stop26h 57m
Wed 12/97:54 pm -
1 stop16h 51m
Deal found 10/29![Frontier logo]()
$181
This Booking.com deal was found by Cheapflights users on 10/26. 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 Booking.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 11/1711:52 am -
1 stop25h 31m
Fri 11/203:04 pm -
1 stop11h 10m
Deal found 10/26![Frontier logo]()
$201
This Mytrip deal was found by Cheapflights users on 10/26. 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.
Sat 12/1211:30 am -
2 stops34h 42m
Mon 12/147:54 pm -
1 stop6h 26m
Deal found 10/26![Frontier logo]()
$213
This Cheapflightsfares deal was found by Cheapflights users on 10/27. 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 Cheapflightsfares is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 11/206:45 am -
1 stop26h 18m
Sat 11/213:04 pm -
1 stop11h 10m
Deal found 10/27![Frontier logo]()
$218
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 October 30, 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 October 30, 2026.
This Mytrip deal was found by Cheapflights users on 10/26. 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.
Wed 12/211:30 am -
2 stops23h 37m
Wed 12/167:54 pm -
2 stops24h 21m
Deal found 10/26![Frontier logo]()
$272
This Southwest deal was found by Cheapflights users on 10/26. 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 Southwest is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 12/1211:20 am -
1 stop7h 05m
Mon 12/148:25 am -
1 stop8h 15m
Deal found 10/26![Southwest logo]()
$355
This Delta deal was found by Cheapflights users on 10/28. 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.
Fri 12/45:04 pm -
1 stop5h 42m
Mon 12/77:08 am -
1 stop7h 09m
Deal found 10/28![Delta logo]()
$375
This Mytrip deal was found by Cheapflights users on 10/30. 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.
Mon 12/217:10 pm -
3 stops19h 32m
Mon 12/282:00 pm -
3 stops20h 01m
Deal found 10/30![Multiple Airlines logo]()
$490
This American Airlines deal was found by Cheapflights users on 10/25. 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 12/157:00 am -
1 stop8h 46m
Wed 12/305:00 am -
1 stop6h 44m
Deal found 10/25![American Airlines logo]()
$551
This United Airlines deal was found by Cheapflights users on 10/25. 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 12/145:00 am -
2 stops29h 22m
Thu 12/175:05 am -
2 stops12h 14m
Deal found 10/25![United Airlines logo]()
$586
This Frontier deal was found by Cheapflights users on 10/29. 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 Frontier is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Mon 11/236:08 pm -
1 stop11h 46m
Fri 11/273:04 pm -
1 stop11h 10m
Deal found 10/29![Frontier logo]()
$372
This Southwest deal was found by Cheapflights users on 10/25. 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 Southwest is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 12/161:55 pm -
1 stop5h 15m
Tue 12/295:05 am -
1 stop6h 05m
Deal found 10/25![Southwest logo]()
$510
This United Airlines deal was found by Cheapflights users on 10/27. 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 12/2211:52 pm -
1 stop8h 50m
Tue 1/51:17 pm -
2 stops10h 58m
Deal found 10/27![United Airlines logo]()
$594
This Mytrip deal was found by Cheapflights users on 10/25. 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.
Wed 11/1111:52 am -
2 stops21h 27m
Sun 11/154:26 pm -
2 stops20h 09m
Deal found 10/25![Frontier logo]()
$560
This United Airlines deal was found by Cheapflights users on 10/27. 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 12/2111:52 pm -
1 stop8h 50m
Tue 1/51:17 pm -
2 stops10h 58m
Deal found 10/27![United Airlines logo]()
$594
Last-minute flights from Ontario to St. LouisDiscover last-minute flight deals from Ontario to St. Louis. Data last updated October 30, 2026 and is based on user searches.
Discover last-minute flight deals from Ontario to St. Louis. Data last updated October 30, 2026 and is based on user searches.
This Mytrip deal was found by Cheapflights users on 10/26. 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.
Wed 11/116:30 am -
1 stop6h 53m
Mon 11/167:59 pm -
1 stop16h 36m
Deal found 10/26![Frontier logo]()
$236
This Booking.com deal was found by Cheapflights users on 10/27. 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 Booking.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Mon 11/166:30 am -
1 stop10h 44m
Tue 11/245:15 pm -
1 stop23h 36m
Deal found 10/27![Frontier logo]()
$240
This Booking.com deal was found by Cheapflights users on 10/26. 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 Booking.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 11/1711:52 am -
1 stop25h 31m
Fri 11/203:04 pm -
1 stop11h 10m
Deal found 10/26![Frontier logo]()
$201
This Mytrip deal was found by Cheapflights users on 10/27. 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.
Wed 11/186:30 am -
1 stop6h 53m
Sun 11/225:15 pm -
1 stop28h 21m
Deal found 10/27![Frontier logo]()
$234
This Mytrip deal was found by Cheapflights users on 10/26. 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.
Thu 11/1911:52 am -
1 stop21h 11m
Sun 11/225:15 pm -
1 stop28h 21m
Deal found 10/26![Frontier logo]()
$265
This Cheapflightsfares deal was found by Cheapflights users on 10/27. 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 Cheapflightsfares is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 11/206:45 am -
1 stop26h 18m
Sat 11/213:04 pm -
1 stop11h 10m
Deal found 10/27![Frontier logo]()
$218
This Booking.com deal was found by Cheapflights users on 10/26. 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 Booking.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 11/2011:40 am -
1 stop21h 23m
Sun 11/225:15 pm -
1 stop23h 36m
Deal found 10/26![Frontier logo]()
$255
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 October 30, 2026.
Search for one-way flight options from Ontario to St. Louis. Find affordable one-way fares based on user searches. Data last updated October 30, 2026.
This Super.com deal was found by Cheapflights users on 10/28. 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 Super.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 12/86:00 am -
1 stop27h 04m
Wed 12/3112:00 am -
Nonstop0h 00m
Deal found 10/28![Frontier logo]()
$67
This Booking.com deal was found by Cheapflights users on 10/28. 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 Booking.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 11/186:30 am -
1 stop6h 53m
Wed 12/3112:00 am -
Nonstop0h 00m
Deal found 10/28![Frontier logo]()
$72
This Super.com deal was found by Cheapflights users on 10/28. 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 Super.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 12/116:00 am -
1 stop26h 57m
Wed 12/3112:00 am -
Nonstop0h 00m
Deal found 10/28![Frontier logo]()
$80
This Mytrip deal was found by Cheapflights users on 10/28. 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 12/1311:30 am -
1 stop21h 27m
Wed 12/3112:00 am -
Nonstop0h 00m
Deal found 10/28![Frontier logo]()
$82
This Kiwi.com deal was found by Cheapflights users on 10/25. 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 12/1511:30 am -
1 stop21h 34m
Wed 12/3112:00 am -
Nonstop0h 00m
Deal found 10/25![Frontier logo]()
$85
This Gotogate deal was found by Cheapflights users on 10/27. 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 Gotogate is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sun 11/226:45 am -
1 stop26h 18m
Wed 12/3112:00 am -
Nonstop0h 00m
Deal found 10/27![Frontier logo]()
$86
This Super.com deal was found by Cheapflights users on 10/26. 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 Super.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 11/1911:52 am -
1 stop21h 11m
Wed 12/3112:00 am -
Nonstop0h 00m
Deal found 10/26![Frontier logo]()
$91
This Trip.com deal was found by Cheapflights users on 10/28. 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 Trip.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 1/156:30 am -
1 stop25h 50m
Wed 12/3112:00 am -
Nonstop0h 00m
Deal found 10/28![Frontier logo]()
$95
This Frontier deal was found by Cheapflights users on 10/28. 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 Frontier is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 12/256:30 am -
1 stop6h 56m
Wed 12/3112:00 am -
Nonstop0h 00m
Deal found 10/28![Frontier logo]()
$98
This Super.com deal was found by Cheapflights users on 10/26. 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 Super.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 2/236:30 am -
1 stop25h 50m
Wed 12/3112:00 am -
Nonstop0h 00m
Deal found 10/26![Frontier logo]()
$102
Find flight deals from Ontario to St. Louis
Discover tips and strategies to find the most affordable flight options for your journey from Ontario (ONT) to St. Louis (STL). Learn about various techniques such as flexible date searches, comparing prices across and setting up price alerts. Use these methods to find the cheapest flights available for your travel needs. Data last updated October 30, 2026.
Most accurate provider | FlightHub 3 stars |
|---|---|
Most trusted provider | FlightHub 3 stars |
Round-trip from | $138 (Mytrip) |
One-way from | $67 (Super.com) |
Popular in | July |
Cheapest in | April |
Average price | $442 |
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 October 30, 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
OntarioSt. Louis
ONT Ontario - STL Lambert-St Louis
ONTSTL
Ontario
Sun 11/22
6:45 am-11:03 am
1 stop26h 18m
Lambert-St Louis
Wed 12/31
12:00 am-10:00 pm
Nonstop0h 00m
$112
OntarioSt. Louis
ONT Ontario - STL Lambert-St Louis
ONTSTL
Ontario
Fri 12/11
2:53 pm-10:57 am
2 stops18h 04m
Lambert-St Louis
Wed 12/31
12:00 am-10:00 pm
Nonstop0h 00m
$120
OntarioSt. Louis
ONT Ontario - STL Lambert-St Louis
ONTSTL
Ontario
Wed 1/13
6:27 pm-4:58 pm
1 stop20h 31m
Lambert-St Louis
Wed 12/31
12:00 am-10:00 pm
Nonstop0h 00m
$134
Quickest round-trip
OntarioSt. Louis
ONT Ontario - STL Lambert-St Louis
ONTSTL
Ontario
Thu 12/31
9:00 am-4:42 pm
1 stop5h 42m
Lambert-St Louis
Wed 12/31
12:00 am-10:00 pm
Nonstop0h 00m
$146
OntarioSt. Louis
ONT Ontario - STL Lambert-St Louis
ONTSTL
Ontario
Tue 12/8
6:00 am-4:40 pm
1 stop8h 40m
Lambert-St Louis
Wed 12/31
12:00 am-10:00 pm
Nonstop0h 00m
$178
OntarioSt. Louis
ONT Ontario - STL Lambert-St Louis
ONTSTL
Ontario
Thu 12/10
12:20 pm-12:05 am
1 stop9h 45m
Lambert-St Louis
Wed 12/31
12:00 am-10:00 pm
Nonstop0h 00m
$178
OntarioSt. Louis
ONT Ontario - STL Lambert-St Louis
ONTSTL
Ontario
Wed 11/11
10:35 am-12:33 pm
1 stop23h 58m
Lambert-St Louis
Wed 12/31
12:00 am-10:00 pm
Nonstop0h 00m
$183
OntarioSt. Louis
ONT Ontario - STL Lambert-St Louis
ONTSTL
Ontario
Mon 12/14
12:20 pm-9:38 pm
1 stop7h 18m
Lambert-St Louis
Wed 12/31
12:00 am-10:00 pm
Nonstop0h 00m
$216
OntarioSt. Louis
ONT Ontario - STL Lambert-St Louis
ONTSTL
Ontario
Wed 12/16
12:20 pm-12:05 am
1 stop9h 45m
Lambert-St Louis
Wed 12/31
12:00 am-10:00 pm
Nonstop0h 00m
$216
OntarioSt. Louis
ONT Ontario - STL Lambert-St Louis
ONTSTL
Ontario
Wed 1/13
11:30 am-8:10 pm
2 stops6h 40m
Lambert-St Louis
Wed 12/31
12:00 am-10:00 pm
Nonstop0h 00m
$221
Showing 1-10 of 22 resultsSorted by cheapest first
Compare providers for flights from Ontario to St. Louis
Provider information is updated monthly. Please note that these providers often have deals for this flight, but the availability may vary on a day-by-day basis on Cheapflights.
Use the table below to compare price accuracy, trust ratings, and cancellation policies for each provider offering flight deals from Ontario to St. Louis in October.
| Provider | Price Accuracy | Trust Score* |
|---|---|---|
| Price Accuracy1 star | Trust Score*3 stars | |
| Price Accuracy3 stars | Trust Score*3 stars | |
| Price Accuracy2 stars | Trust Score*3 stars | |
| Price Accuracy- | Trust Score*1 star |
- Most accurate provider: When it comes to deals on Ontario-St. Louis flights, users find the pricing of FlightHub to be most consistent on Cheapflights vs. FlightHub Users can find the same prices on Ontario-St. Louis flight deals on Cheapflights vs. FlightHub >95% of the time. Price accuracy is based on data collected from Ontario-St. Louis flight searches over the past month and is updated monthly.
- Most trusted provider: When it comes to deals on Ontario-St. Louis flights, Cheapflights users trust FlightHub the most. FlightHub has received a user feedback score of 3 out of 3 stars (3 being the best), meaning they have been trusted the most by Cheapflights users looking for Ontario-St. Louis flight deals. Provider user feedback score is based on Cheapflights searches over the past month and is updated monthly.
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.
ONT-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
What is the cheapest month to book a flight from Ontario to St. Louis?
Currently, April is the cheapest month in which you can book a flight from Ontario to St. Louis (average of $250). Flying from Ontario to St. Louis in July is currently the most expensive (average of $596). 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.
How much does it cost to fly round-trip from Ontario to St. Louis?
Airfare is below average for this route at the moment.
Ontario to St. Louis flights typically cost between $206 and $382 in December.The cheapest round-trip price found within the last 5 days was $138 on Frontier (Dec 4-Dec 7).
Reviews of airlines servicing St. Louis
Get insights into the airlines that provide service to St. Louis. 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 St. Louis. Reviews last updated October 30, 2026.
Get a feel of what it's like to fly with Southwest,Delta, andUnited Airlines from Ontario to St. Louis by reading reviews from past customers. Users have also rated airlines in terms of entertainment options, comfort, food, crew/service, and boarding process.
Comfort
8.0
Food
7.0
Entertainment
7.4
Boarding
8.1
Crew
8.6
Overall
7.9
Reviews
1 / 20
10.0
ExcellentCourtney,Sep 2026
DEN - STL
Comfort
8.0
Food
7.0
Entertainment
7.4
Boarding
8.1
Crew
8.6
Overall
7.9
Reviews
1 / 20
10.0
ExcellentCourtney,Sep 2026
DEN - STL
Comfort
8.0
Food
7.0
Entertainment
7.4
Boarding
8.1
Crew
8.6
Overall
7.9
Reviews
1 / 20
10.0
ExcellentCourtney,Sep 2026
DEN - STL
Comfort
8.0
Food
7.0
Entertainment
7.4
Boarding
8.1
Crew
8.6
Overall
7.9
Reviews
1 / 20
10.0
ExcellentCourtney,Sep 2026
DEN - STL
Comfort
8.0
Food
7.0
Entertainment
7.4
Boarding
8.1
Crew
8.6
Overall
7.9
Reviews
1 / 20
10.0
ExcellentCourtney,Sep 2026
DEN - STL
Comfort
8.0
Food
7.0
Entertainment
7.4
Boarding
8.1
Crew
8.6
Overall
7.9
Reviews
1 / 20
10.0
ExcellentCourtney,Sep 2026
DEN - STL
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
Collinsville
Edwardsville
Glencoe
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Ontario and St. Louis flights
Browse other Ontario and St. Louis flight options. Last updated on October 30, 2026.
Other flights from Ontario
Browse through other flights departing from Ontario. Flights are based on user searches made on Cheapflights and were last updated on October 30, 2026.
Popular flight searches
Check out other popular destinations found by fellow travelers in 2026
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 October 30, 2026.
Top 5 airlines flying from Ontario to St. Louis
Discover the top 5 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 October 30, 2026.
| Airline | Cheapest | Average | Flexibility | On-time |
|---|---|---|---|---|
| Cheapest$170 | Average$271 | FlexibilityNo cancel fee | On-time62% | |
| Cheapest$280 | Average$442 | FlexibilityNo cancel fee | On-timeN/A | |
| Cheapest$292 | Average$467 | FlexibilityNo cancel fee | On-time71% | |
| Cheapest$325 | Average$640 | FlexibilityNo cancel fee | On-time69% | |
| Cheapest$346 | Average$498 | FlexibilityNo cancel fee | On-time63% |