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Cheap flights from St. Louis to Ontario from $135

This is the cheapest one-way flight price found by a momondo user in the last 72 hours by searching for a flight from St. Louis to Ontario departing on 3/31. Fares may change, and may not be available for all flights or travel dates. Click the price to refresh the search for this deal.
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0 bags

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Find the cheapest flights from St. Louis to Ontario

Cheap round-trip flights

Enter your travel dates to find the best prices.
Multiple Airlines Logo
3:49 pm - 2:20 pm
STL
-
YYZ
21h 31m
1 stop
Multiple Airlines Logo
2:20 pm - 10:37 am
YYZ
-
STL
21h 17m
2 stops
$245Multiple Airlines
mar., mar. 3 - mar., mar. 17
Multiple Airlines Logo
3:49 pm - 2:20 pm
STL
-
YYZ
21h 31m
1 stop
Multiple Airlines Logo
3:40 pm - 10:37 am
YYZ
-
STL
19h 57m
2 stops
$262Multiple Airlines
mar., mar. 3 - mar., mar. 17
Multiple Airlines Logo
3:49 pm - 2:20 pm
STL
-
YYZ
21h 31m
1 stop
Multiple Airlines Logo
7:15 am - 11:19 pm
YYZ
-
STL
17h 04m
1 stop
$316Multiple Airlines
mar., mar. 3 - mar., mar. 17
Multiple Airlines Logo
3:49 pm - 2:20 pm
STL
-
YYZ
21h 31m
1 stop
Multiple Airlines Logo
4:45 pm - 11:59 pm
YYZ
-
STL
32h 14m
1 stop
$318Multiple Airlines
mar., mar. 3 - mar., mar. 17
Multiple Airlines Logo
6:41 pm - 6:20 am
STL
-
YYZ
10h 39m
1 stop
Multiple Airlines Logo
11:15 am - 6:51 am
YYZ
-
STL
20h 36m
2 stops
$337Multiple Airlines
sáb., feb. 14 - mar., feb. 17
American Airlines Logo
6:00 am - 3:04 pm
STL
-
YUL
8h 04m
1 stop
American Airlines Logo
3:45 pm - 10:13 am
YUL
-
STL
19h 28m
1 stop
$368American Airlines
mar., feb. 17 - vie., feb. 20
United Airlines Logo
7:00 am - 1:32 pm
STL
-
YOW
5h 32m
1 stop
United Airlines Logo
6:00 am - 10:41 am
YOW
-
STL
5h 41m
1 stop
$369United Airlines
jue., feb. 5 - mié., feb. 11
American Airlines Logo
10:37 am - 10:56 pm
STL
-
YUL
11h 19m
2 stops
American Airlines Logo
3:45 pm - 10:13 am
YUL
-
STL
19h 28m
1 stop
$378American Airlines
mar., feb. 17 - vie., feb. 20
Air Canada Logo
6:30 am - 4:30 pm
STL
-
YOW
9h 00m
2 stops
Air Canada Logo
12:00 pm - 8:58 pm
YOW
-
STL
9h 58m
2 stops
$409Air Canada
jue., feb. 5 - mié., feb. 11
United Airlines Logo
7:00 pm - 2:30 pm
STL
-
YOW
18h 30m
2 stops
United Airlines Logo
6:20 am - 9:07 pm
YOW
-
STL
15h 47m
1 stop
$455United Airlines
dom., mar. 8 - dom., mar. 15

American Airlines flights from St. Louis to Region of Ontario

Our best American Airlines deals on St. Louis to Region of Ontario flight tickets
American Airlines
Feb 17
STL6:00 amLambert-St Louis
8h 04m
1 stop
YUL3:04 pmMontreal Pierre Elliott Trudeau Intl
Feb 20
YUL3:45 pmMontreal Pierre Elliott Trudeau Intl
19h 28m
1 stop
STL10:13 amLambert-St Louis
$368
American Airlines
Feb 17
STL10:37 amLambert-St Louis
11h 19m
2 stops
YUL10:56 pmMontreal Pierre Elliott Trudeau Intl
Feb 20
YUL3:45 pmMontreal Pierre Elliott Trudeau Intl
19h 28m
1 stop
STL10:13 amLambert-St Louis
$378
American Airlines
Feb 14
STL6:36 pmLambert-St Louis
15h 22m
1 stop
YYZ10:58 amToronto Pearson Intl
Feb 21
YYZ1:10 pmToronto Pearson Intl
9h 02m
1 stop
STL9:12 pmLambert-St Louis
$389

WestJet flights from St. Louis to Region of Ontario

Our best WestJet deals on St. Louis to Region of Ontario flight tickets
WestJet
Feb 27
STL5:29 pmLambert-St Louis
21h 21m
2 stops
YYZ3:50 pmToronto Pearson Intl
Mar 1
YYZ6:10 amToronto Pearson Intl
11h 32m
1 stop
STL4:42 pmLambert-St Louis
$476
WestJet
Jan 31
STL6:10 amLambert-St Louis
8h 43m
2 stops
YYZ3:53 pmToronto Pearson Intl
Feb 1
YYZ7:45 amToronto Pearson Intl
13h 58m
1 stop
STL8:43 pmLambert-St Louis
$609
WestJet
Jun 8
STL1:30 pmLambert-St Louis
10h 10m
2 stops
YUL12:40 amMontreal Pierre Elliott Trudeau Intl
Jun 12
YUL6:45 amMontreal Pierre Elliott Trudeau Intl
10h 13m
2 stops
STL3:58 pmLambert-St Louis
$694

momondo Fare Finder

 
Customize your flight search to find flights from St. Louis to Region of 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, momondo users made 832,500 searches. Data last updated enero 24, 2026.
Use the filters below to find and compare flights from St. Louis to Ontario that are best for you.

Fly from

Fly to

Route

Depart

Return

Price

St. LouisToronto

STL - YYZ

STLYYZ

Lambert-St Louis

mar. 3/3

3:49 pm-2:20 pm

1 stop21h 31m

Toronto Pearson Intl

mar. 3/17

2:20 pm-10:37 am

2 stops21h 17m

$245

St. LouisToronto

STL - YYZ

STLYYZ

Lambert-St Louis

mar. 3/3

3:49 pm-2:20 pm

1 stop21h 31m

Toronto Pearson Intl

mar. 3/17

3:40 pm-10:37 am

2 stops19h 57m

$262

St. LouisToronto

STL - YYZ

STLYYZ

Lambert-St Louis

mar. 3/3

3:49 pm-2:20 pm

1 stop21h 31m

Toronto Pearson Intl

mar. 3/17

7:15 am-11:19 pm

1 stop17h 04m

$316

St. LouisToronto

STL - YYZ

STLYYZ

Lambert-St Louis

mar. 3/3

3:49 pm-2:20 pm

1 stop21h 31m

Toronto Pearson Intl

mar. 3/17

4:45 pm-11:59 pm

1 stop32h 14m

$318

St. LouisToronto

STL - YYZ

STLYYZ

Lambert-St Louis

sáb. 2/14

6:41 pm-6:20 am

1 stop10h 39m

Toronto Pearson Intl

mar. 2/17

11:15 am-6:51 am

2 stops20h 36m

$337

St. LouisMontreal

STL - YUL

STLYUL

Lambert-St Louis

mar. 2/17

6:00 am-3:04 pm

1 stop8h 04m

Montreal Pierre Elliott Trudeau Intl

vie. 2/20

3:45 pm-10:13 am

1 stop19h 28m

$368

St. LouisOttawa

STL - YOW

STLYOW

Lambert-St Louis

jue. 2/5

7:00 am-1:32 pm

1 stop5h 32m

Ottawa

mié. 2/11

6:00 am-10:41 am

1 stop5h 41m

$369

St. LouisMontreal

STL - YUL

STLYUL

Lambert-St Louis

mar. 2/17

10:37 am-10:56 pm

2 stops11h 19m

Montreal Pierre Elliott Trudeau Intl

vie. 2/20

3:45 pm-10:13 am

1 stop19h 28m

$378

St. LouisOttawa

STL - YOW

STLYOW

Lambert-St Louis

jue. 2/5

6:30 am-4:30 pm

2 stops9h 00m

Ottawa

mié. 2/11

12:00 pm-8:58 pm

2 stops9h 58m

$409

St. LouisOttawa

STL - YOW

STLYOW

Lambert-St Louis

dom. 3/8

7:00 pm-2:30 pm

2 stops18h 30m

Ottawa

dom. 3/15

6:20 am-9:07 pm

1 stop15h 47m

$455

Flights are sorted by cheapest round-trip flights first.

Showing 1-10 of 20 resultsSorted by cheapest first
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See travel insights to Ontario from

How to get the cheapest flight ticket from St. Louis to Region of Ontario

Look no further. We've gone through all the searches for this route on momondo so you have the important information and insights to find the cheapest flight ticket for your trip

What is the cheapest month to fly to Region of Ontario?

The month of April is, on average, the cheapest month to fly to Region of Ontario from St. Louis, with most prices found around $314. If you aren’t able to travel during the month of April, then book flights to Region of Ontario from St. Louis during June instead. Flights to Region of Ontario in June, while not as cheap as those in April, still average around $363.

What is the cheapest day to depart on your flight to Region of Ontario?

According to our data, Tuesday is the cheapest day to fly to Region of Ontario from St. Louis. The lowest ticket price found for a Tuesday departure recently was $801. Keep in mind that prices can always vary depending on your route and whether or not you are flying domestic or international. Flights from St. Louis to Region of Ontario on a Saturday will generally be more expensive and average around $984. Keep in mind that these prices on both days could fluctuate depending on the season and the demand.

What is the cheapest time of day to depart on your flight to Region of Ontario?

According to our data, the cheapest time of day to fly to Region of Ontario is in the afternoon. momondo users have found flights departing from St. Louis to Region of Ontario in the afternoon for as low as $872. Keep in mind that these prices may fluctuate based on what airline you choose and the time of year you plan to travel. Flights at noon are often more expensive with an average ticket price of $1,150.

What is the cheapest Lambert-St Louis to Ontario flight route?

Fly from Lambert-St Louis to Toronto Pearson Intl for the best Lambert-St Louis - Ontario flight prices

How far in advance should I book a flight to Region of Ontario?

You are more likely to see cheaper flights to Region of Ontario from St. Louis when booking weeks ahead of your departure date. In general, you can expect to find flights to Region of Ontario for around $534 when searching weeks out. However, flight prices might be lower outside of this timeframe. For example, people recently found flights to Region of Ontario from St. Louis for as low as $221 on momondo.

What cabin class options are available on Lambert-St Louis to Ontario flights?

There are 4 cabin classes available to choose from on Lambert-St Louis to Ontario flights. Cabin price and availability will vary by airline so perform a search above to find the right deals for you.

Can stopping save me money on St. Louis to Region of Ontario flights?

You could potentially save up to 24% on your flight if you consider stops on a St. Louis to Region of Ontario flight.

Cheap St. Louis to Region of Ontario flight deals and tips

Find info about flight duration, direct flights, and airports for your flight from St. Louis to Region of Ontario

Best Price Found

$271

Fastest flight time

1h 51m

Direct flights

Every day

Airports in Region of Ontario

123 airports
The best one-way flight to Region of Ontario from St. Louis in the past 72 hours is $271. The best round-trip flight deal from St. Louis to Region of Ontario found on momondo in the last 72 hours is $648.
The fastest flight from St. Louis to Region of Ontario takes 1h 51m
Direct flights go from St. Louis to Region of Ontario every day.
There are 123 airports in Region of Ontario. From St. Louis there are direct flights to Montreal Pierre Elliott Trudeau Intl (YUL), Toronto Pearson Intl (YYZ).
Search flight deals

  • When did momondo last update prices for flights from Lambert-St Louis Airport to Ontario?

    Prices for flights from Lambert-St Louis Airport to Ontario were last updated today.

  • How many operators does momondo search for flights from Lambert-St Louis Airport to Ontario?

  • How old do you have to be to fly from Lambert-St Louis Airport to Ontario?

    The minimum age for a child to fly alone is five, but airlines offering an unaccompanied minor (UNMR) service may have their age restrictions, such as regulations concerning flight duration, timing, and layovers. It is recommended that you verify with the airline you are booking with for travel from Lambert-St Louis Airport to Ontario.

  • What documentation or ID do you need to fly to Ontario?

    The required travel and health documents for your Ontario trip may vary depending on your itinerary and personal circumstances. As a general rule, you should carry multiple documents, including a national ID card or driver's license and a passport valid for six months after your intended arrival at Ontario. We recommend that you seek guidance from your airline or a reliable third party such as IATA.

  • What is the most popular plane model from St. Louis to Region of Ontario?

Best airlines flying from St. Louis to Region of Ontario

Compare and see reviews for airlines that fly from St. Louis to Region of Ontario with momondo
Airline
Rating
Free Cancellation
Price
United AirlinesPriceFrom $199Free CancellationRating
7.4
9,193 reviews
Search United Airlines flights
Air CanadaPriceFrom $214Free CancellationRating
7.1
10,652 reviews
Search Air Canada flights
American AirlinesPriceFrom $270Free CancellationRating
7.2
11,193 reviews
Search American Airlines flights

Why use momondo?

Why should I use momondo to find a flight deal from St. Louis to Ontario?

It is quick and easy to find St. Louis to Ontario flights on momondo. We search and return numerous flight options from various airlines and agents. You can then use our filters to narrow your search until you have found the most convenient flight to Ontario that suits you.

Can I find flights from St. Louis to Ontario with flexible booking policies on momondo?

Yes. All flights to Ontario from St. Louis on momondo can be compared and filtered by various policies on offer, including flexible booking.

How can momondo help me find flights from St. Louis to Ontario?

Once you have performed a search for St. Louis to Ontario flights, momondo helps you find the right one by offering useful filters to narrow down your flight selection. Flights can be filtered by multiple factors such as airline, airport and price; but also by other criteria like aircraft type and payment method.

I’m not ready to book a flight from St. Louis to Ontario right now. Can momondo alert me if prices change?

If you are simply researching potential flights to Ontario, momondo offers a useful price alert feature which will track prices for flights to Ontario from St. Louis and alert you when they change.

An easier way to manage your Region of Ontario trip

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Find better results for your trip to Ontario

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