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Cheap flights from Seattle to Ontario from C$ 141

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 18/11. Fares are subject to change and may not be available on all flights or dates of travel.
SEA — YYZ
27 Nov — 4 Dec1
1 adult
1 adult, Economy, 0 bags

Find flight deals from Seattle to Ontario

Enter your travel dates to find the best prices.

Cheapest flights from Seattle to Ontario
Explore the most affordable flight options available from Seattle to Ontario. Find the lowest fares from popular airlines and budget airlines, with prices last updated on 28 October 2025.

Sat 29/117:57 a.m.SEA - YYZ
Nonstop4h 38mAlaska Airlines
Sat 6/124:45 p.m.YYZ - SEA
Nonstop5h 33mAlaska Airlines
Deal found 26/10C$ 313
Wed 3/123:15 p.m.SEA - YYZ
2 stops11h 43mWestJet
Wed 10/127:00 a.m.YYZ - SEA
1 stop10h 20mWestJet
Deal found 26/10C$ 318
Sat 29/117:57 a.m.SEA - YYZ
Nonstop4h 38mAlaska Airlines
Tue 2/124:45 p.m.YYZ - SEA
Nonstop5h 33mAlaska Airlines
Deal found 27/10C$ 320
Sat 29/1111:55 a.m.SEA - YYZ
2 stops8h 44mWestJet
Tue 2/127:45 a.m.YYZ - SEA
1 stop9h 35mWestJet
Deal found 27/10C$ 324
Sat 6/1211:55 a.m.SEA - YYZ
2 stops8h 44mWestJet
Wed 10/127:45 a.m.YYZ - SEA
1 stop9h 35mWestJet
Deal found 26/10C$ 327
Wed 3/123:15 p.m.SEA - YYZ
2 stops11h 43mWestJet
Sun 7/127:45 a.m.YYZ - SEA
1 stop9h 35mWestJet
Deal found 27/10C$ 330
Tue 2/127:55 a.m.SEA - YYZ
Nonstop4h 40mMultiple Airlines
Sun 7/127:45 a.m.YYZ - SEA
1 stop9h 35mMultiple Airlines
Deal found 26/10C$ 333
Fri 12/123:10 p.m.SEA - YYZ
2 stops11h 48mWestJet
Tue 16/127:45 a.m.YYZ - SEA
1 stop9h 35mWestJet
Deal found 27/10C$ 334
Sat 29/1111:55 a.m.SEA - YYZ
2 stops8h 44mWestJet
Sat 6/1210:15 p.m.YYZ - SEA
2 stops15h 07mWestJet
Deal found 26/10C$ 336
Thu 4/123:10 p.m.SEA - YYZ
2 stops11h 48mWestJet
Sun 7/127:45 a.m.YYZ - SEA
1 stop9h 35mWestJet
Deal found 28/10C$ 340
Sat 29/117:57 a.m.SEA - YYZ
Nonstop4h 38mMultiple Airlines
Sat 6/1210:15 p.m.YYZ - SEA
2 stops15h 07mMultiple Airlines
Deal found 26/10C$ 341
Thu 20/117:55 a.m.SEA - YYZ
Nonstop4h 40mMultiple Airlines
Mon 24/117:45 a.m.YYZ - SEA
1 stop9h 35mMultiple Airlines
Deal found 26/10C$ 343

Cheap flight deals from Seattle to Ontario

Keep the following information in mind while searching for Seattle to Ontario flight deals. Data was last updated 28 October 2025.

Round-trip from

C$ 313

One-way from

C$ 141

Popular in

June

Cheapest in

January

Average price

C$ 618

Good round-trip deal

C$ 380 or less

Good one-way deal

C$ 223 or less
Alaska Airlines
  • Alaska Airlines
  • 29/11-6/12
  • Nonstop
  • 10h 11m total
  • Seattle to Ontario
Search Deals
Alaska Airlines
  • Alaska Airlines
  • 18/11
  • Nonstop
  • 4h 40m total
  • Seattle to Ontario
Search Deals
Highest demand for flights based on searches. 14% potential increase in price (C$ 130 potential increase over avg. RT price).
Search Deals
Cheapest flight prices on average. 2% potential price decrease (C$ 19 potential savings vs. average RT price).
Search Deals
Average for round-trip flights in October 2025
Search Deals
Price to beat on a round-trip flight from Seattle/Tacoma Intl to Ontario.
Search Deals
Price to beat on a one-way flight from Seattle/Tacoma Intl to Ontario.
Search Deals

Cheapflights Fare Finder

 
Customize your flight search to find flights from Seattle 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 28 October 2025.
Use the filters below to find and compare flights from Seattle to Ontario that are best for you.

Fly from

Seattle

Fly to

Ontario

Route

Depart

Return

Price

SeattleToronto

SEA - YYZ

SEAYYZ

Seattle/Tacoma Intl

Sat 15/11

7:55 a.m.-3:35 p.m.

Nonstop4h 40m

Toronto Pearson Intl

Wed 19/11

4:45 p.m.-7:05 p.m.

Nonstop5h 20m

C$ 351

SeattleToronto

SEA - YYZ

SEAYYZ

Seattle/Tacoma Intl

Sat 6/12

7:55 a.m.-3:35 p.m.

Nonstop4h 40m

Toronto Pearson Intl

Sat 13/12

4:45 p.m.-7:18 p.m.

Nonstop5h 33m

C$ 351

SeattleToronto

SEA - YYZ

SEAYYZ

Seattle/Tacoma Intl

Wed 3/12

7:55 a.m.-3:35 p.m.

Nonstop4h 40m

Toronto Pearson Intl

Wed 10/12

4:45 p.m.-7:18 p.m.

Nonstop5h 33m

C$ 351

SeattleToronto

SEA - YYZ

SEAYYZ

Seattle/Tacoma Intl

Wed 18/2

8:00 a.m.-3:35 p.m.

Nonstop4h 35m

Toronto Pearson Intl

Sat 21/2

4:45 p.m.-7:05 p.m.

Nonstop5h 20m

C$ 351

SeattleToronto

SEA - YYZ

SEAYYZ

Seattle/Tacoma Intl

Thu 19/2

8:00 a.m.-3:35 p.m.

Nonstop4h 35m

Toronto Pearson Intl

Sat 21/2

4:45 p.m.-7:05 p.m.

Nonstop5h 20m

C$ 366

SeattleToronto

SEA - YYZ

SEAYYZ

Seattle/Tacoma Intl

Wed 19/11

7:55 a.m.-3:35 p.m.

Nonstop4h 40m

Toronto Pearson Intl

Fri 21/11

4:45 p.m.-7:17 p.m.

Nonstop5h 32m

C$ 366

SeattleToronto

SEA - YYZ

SEAYYZ

Seattle/Tacoma Intl

Sun 11/1

7:55 a.m.-3:35 p.m.

Nonstop4h 40m

Toronto Pearson Intl

Sat 17/1

4:45 p.m.-7:21 p.m.

Nonstop5h 36m

C$ 366

SeattleToronto

SEA - YYZ

SEAYYZ

Seattle/Tacoma Intl

Sun 15/2

8:00 a.m.-3:35 p.m.

Nonstop4h 35m

Toronto Pearson Intl

Tue 17/2

4:45 p.m.-7:05 p.m.

Nonstop5h 20m

C$ 366

SeattleOttawa

SEA - YOW

SEAYOW

Seattle/Tacoma Intl

Tue 10/3

12:45 p.m.-10:26 a.m.

2 stops18h 41m

Ottawa

Wed 11/3

2:15 p.m.-8:35 p.m.

1 stop9h 20m

C$ 369

SeattleHamilton

SEA - YHM

SEAYHM

Seattle/Tacoma Intl

Wed 18/2

3:10 p.m.-5:16 p.m.

1 stop23h 06m

Hamilton

Sun 22/2

6:10 p.m.-2:19 p.m.

1 stop23h 09m

C$ 383

Flights are sorted by cheapest round-trip flights first.

Deals found on 25/10

Showing 1-10 of 60 results
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Best time to book a flight from Seattle to Ontario

Have a flexible travel schedule? Discover the best time to fly to Ontario from Seattle 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 Seattle to Ontario

What is the cheapest month to book a flight from Seattle to Region of Ontario?

Currently, March is the cheapest month in which you can book a flight from Seattle to Region of Ontario (average of C$ 169). Flying from Seattle to Region of Ontario in May is currently the most expensive (average of C$ 379). 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 SEA to ON?

Find hourly flight availability from Seattle 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 28 October 2025.

When flying from Seattle to Region of Ontario, the time of day you fly usually plays a role in the price. Save by searching for a flight in the evening, which can drop the price by up to 22% versus a flight in the morning.

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 28 October 2025.
Check out reviews from past customers who have flown with Alaska Airlines,United Airlines, andWestJet from Seattle to Ontario to help guide your decision. Users have also rated airlines in terms of entertainment options, comfort, food, crew/service, and boarding process.
Alaska Airlines
8.0
Very good
11,199 reviews
Check prices

Boarding

8.1

Overall

8.0

Comfort

7.8

Food

7.1

Entertainment

7.0

Crew

8.5

Reviews

1 / 20
8.0
Excellent

Anonymous,Sep 2025

SEA - MKE

The crew were excellent, flight good, but the actual space for a person to occupy for 4 hours seems to get smaller and smaller 🤣. I am not overweight, and average height….very uncomfortable,, especially when I couldn’t recliner the seat at all, and the pocket in front doesn’t accommodate a water bottle.
Alaska Airlines
8.0
Very good
11,199 reviews
Alaska Airlines
8.0
Very good
11,199 reviews
Check prices

Boarding

8.1

Overall

8.0

Comfort

7.8

Food

7.1

Entertainment

7.0

Crew

8.5

Reviews

1 / 20
8.0
Excellent

Anonymous,Sep 2025

SEA - MKE

The crew were excellent, flight good, but the actual space for a person to occupy for 4 hours seems to get smaller and smaller 🤣. I am not overweight, and average height….very uncomfortable,, especially when I couldn’t recliner the seat at all, and the pocket in front doesn’t accommodate a water bottle.
United Airlines
7.4
Good
8,997 reviews
Alaska Airlines
8.0
Very good
11,199 reviews
Check prices

Boarding

8.1

Overall

8.0

Comfort

7.8

Food

7.1

Entertainment

7.0

Crew

8.5

Reviews

1 / 20
8.0
Excellent

Anonymous,Sep 2025

SEA - MKE

The crew were excellent, flight good, but the actual space for a person to occupy for 4 hours seems to get smaller and smaller 🤣. I am not overweight, and average height….very uncomfortable,, especially when I couldn’t recliner the seat at all, and the pocket in front doesn’t accommodate a water bottle.
WestJet
7.2
Good
3,148 reviews
Alaska Airlines
8.0
Very good
11,199 reviews
Check prices

Boarding

8.1

Overall

8.0

Comfort

7.8

Food

7.1

Entertainment

7.0

Crew

8.5

Reviews

1 / 20
8.0
Excellent

Anonymous,Sep 2025

SEA - MKE

The crew were excellent, flight good, but the actual space for a person to occupy for 4 hours seems to get smaller and smaller 🤣. I am not overweight, and average height….very uncomfortable,, especially when I couldn’t recliner the seat at all, and the pocket in front doesn’t accommodate a water bottle.
Air Canada
7.1
Good
10,371 reviews
Alaska Airlines
8.0
Very good
11,199 reviews
Check prices

Boarding

8.1

Overall

8.0

Comfort

7.8

Food

7.1

Entertainment

7.0

Crew

8.5

Reviews

1 / 20
8.0
Excellent

Anonymous,Sep 2025

SEA - MKE

The crew were excellent, flight good, but the actual space for a person to occupy for 4 hours seems to get smaller and smaller 🤣. I am not overweight, and average height….very uncomfortable,, especially when I couldn’t recliner the seat at all, and the pocket in front doesn’t accommodate a water bottle.

Related info for your journey

Find useful and relevant information for your journey from Seattle 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 Seattle to Ontario?

    Located just 18.4 km from the city centre, Seattle/Tacoma Intl (SEA) is the airport most travellers will use when flying to Ontario from Seattle.

  • How long is the flight from Seattle to Region of Ontario?

    There are many flights that can get you from Seattle to Region of Ontario in 4h 40m. Fly via Alaska Airlines, United Airlines, or WestJet to get the fastest option. Airlines will cover a distance of 3306 km. Both multi-stop and direct flights can be found to your destination and back.

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

    The cheapest airlines for a one-way flight from Seattle to Region of Ontario are Alaska Airlines (C$ 141), WestJet (C$ 182), and Air Canada (C$ 200).

  • What are the most popular routes from Seattle to Region of Ontario?

    When deciding which route to take from Seattle to Region of Ontario consider Seattle/Tacoma Intl - Toronto Pearson Intl, Seattle/Tacoma Intl - Montreal Pierre Elliott Trudeau Intl or Seattle/Tacoma Intl - Toronto Island as they are the most popular.

  • What are the most reliable airlines from Seattle to Region of Ontario?

    Consider Qatar Airways (97%), Alaska Airlines (97%) or Air Tahiti Nui (96%) when booking your flight. These represent the most reliable airlines when flying from Seattle to Region of Ontario.

  • What are the cheapest flights from Seattle to Region of Ontario?

    The cheapest flight price from Seattle to Region of Ontario is C$ 155. On average you can expect to pay C$ 557. The most popular route, (Seattle/Tacoma Intl - Toronto Pearson Intl), can usually be booked for C$ 319.

  • Can I find deals for flights from Seattle to Ontario that include hotel bookings?

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

  • How can I find direct flights from Seattle to Ontario?

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

  • Can I find deals for business class flights from Seattle to Ontario?

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

    Currently, March is the cheapest month in which you can book a flight from Seattle to Region of Ontario (average of C$ 169). Flying from Seattle to Region of Ontario in May is currently the most expensive (average of C$ 379). 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 Seattle to Ontario

See prices for flight routes from nearby airports that may be better suited for you.
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Top 4 airlines flying from Seattle to Ontario

Discover the top 4 airlines that operate flights from Seattle 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 28 October 2025.
AirlineCheapestAverageFlexibilityOn-time
WestJetCheapestC$ 289AverageC$ 395FlexibilityNo cancel feeOn-time60%
Search WestJet flights
Air CanadaCheapestC$ 327AverageC$ 569FlexibilityNo cancel feeOn-time67%
Search Air Canada flights
Alaska AirlinesCheapestC$ 373AverageC$ 759FlexibilityNo cancel feeOn-time75%
Search Alaska Airlines flights
United AirlinesCheapestC$ 486AverageC$ 546FlexibilityNo cancel feeOn-time69%
Search United Airlines 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 Seattle to Ontario?

Cheapflights goes through 900+ travel sites to look for the best flight deals for flights from Seattle to Ontario. Too many options? Cheapflights also provides filters for things like airlines, price ranges, and number of stops to help you make a decision easily.

Why should you use Cheapflights to find cheap flight tickets from Seattle to Ontario?

Cheapflights simply makes it quick and affordable to book flights from Seattle to Ontario by bringing together all flight options from hundreds of airlines and agencies online — and put it in one place for you to choose from. Plus, Cheapflights is 100% free to use for all.

Can Cheapflights find flights from Seattle to Ontario with no change fees?

Users can book flights with no change fees policies with our dedicated filters. Book flights from Seattle to Ontario flexibly with Cheapflights today.

Can Cheapflights notify me if prices for flights from Seattle to Ontario become cheaper?

Yes, and it’s super simple to set up. Click the bell icon next to the flight deals above and provide a valid email address to enable Price Alerts. That’s it!

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