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$185+ Cheap flights from Ontario to Seattle (SEA)

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 10/10. Fares are subject to change and may not be available on all flights or dates of travel.
YYZ — SEA
Jul 29 — Aug 51
Wed 7/29
Wed 8/5
1 adult, Economy
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Cheap flight deals from Ontario to Seattle

Cheapest flights from Ontario to Seattle
Explore the most affordable flight options available from Ontario to Seattle. Find the lowest fares from popular airlines and budget airlines, with prices last updated on June 29, 2026.

This Booking.com deal was found by Cheapflights users on 6/25. 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 Booking.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 10/287:45 am
YYZ
-
SEA
1 stop9h 35m
WestJet
Sat 10/313:20 pm
SEA
-
YYZ
2 stops11h 38m
WestJet
Deal found 6/25$273
This Justfly.com deal was found by Cheapflights users on 6/28. 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 Justfly.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 11/206:30 am
YYZ
-
SEA
1 stop9h 50m
WestJet
Mon 11/233:10 pm
SEA
-
YYZ
2 stops10h 48m
WestJet
Deal found 6/28$274
This oojo deal was found by Cheapflights users on 6/25. 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 oojo is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 11/46:30 am
YYZ
-
SEA
1 stop9h 50m
WestJet
Wed 11/183:10 pm
SEA
-
YYZ
2 stops10h 48m
WestJet
Deal found 6/25$277
This oojo deal was found by Cheapflights users on 6/25. 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 oojo is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 10/2112:00 pm
YYZ
-
SEA
1 stop9h 45m
WestJet
Mon 10/263:10 pm
SEA
-
YYZ
2 stops11h 48m
WestJet
Deal found 6/25$289
This oojo deal was found by Cheapflights users on 6/26. 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 oojo is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 11/256:30 am
YYZ
-
SEA
1 stop9h 50m
WestJet
Sun 11/293:10 pm
SEA
-
YYZ
2 stops28h 33m
WestJet
Deal found 6/26$290
This FlightHub deal was found by Cheapflights users on 6/27. 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 FlightHub is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 10/112:00 pm
YYZ
-
SEA
1 stop9h 45m
WestJet
Wed 11/113:10 pm
SEA
-
YYZ
2 stops10h 48m
WestJet
Deal found 6/27$293
This FlightHub deal was found by Cheapflights users on 6/27. 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 FlightHub is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 10/31:30 pm
YYZ
-
SEA
1 stop8h 15m
WestJet
Sat 10/107:35 pm
SEA
-
YYZ
1 stop7h 10m
WestJet
Deal found 6/27$296
This oojo deal was found by Cheapflights users on 6/27. 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 oojo is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 10/141:30 pm
YYZ
-
SEA
1 stop8h 15m
WestJet
Wed 11/183:10 pm
SEA
-
YYZ
2 stops10h 48m
WestJet
Deal found 6/27$297
This oojo deal was found by Cheapflights users on 6/27. 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 oojo is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 10/2412:40 pm
YYZ
-
SEA
2 stops9h 05m
WestJet
Mon 10/263:10 pm
SEA
-
YYZ
2 stops11h 48m
WestJet
Deal found 6/27$298
This Justfly.com deal was found by Cheapflights users on 6/26. 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 Justfly.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 10/11:30 pm
YYZ
-
SEA
1 stop8h 15m
WestJet
Tue 10/67:35 pm
SEA
-
YYZ
1 stop8h 20m
WestJet
Deal found 6/26$299
This FlightHub deal was found by Cheapflights users on 6/25. 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 FlightHub is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 10/211:30 pm
YYZ
-
SEA
1 stop8h 15m
WestJet
Sat 10/2410:30 am
SEA
-
YYZ
1 stop9h 15m
WestJet
Deal found 6/25$302
This oojo deal was found by Cheapflights users on 6/25. 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 oojo is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 9/96:10 am
YXU
-
SEA
1 stop15h 35m
WestJet
Thu 9/107:35 pm
SEA
-
YXU
1 stop6h 45m
WestJet
Deal found 6/25$347

Find flight deals from Ontario to Seattle

Keep the following information in mind while searching for Ontario to Seattle flight deals. Data was last updated June 29, 2026.

Most accurate provider

FlightHub
3 stars

Most trusted provider

FlightHub
3 stars

Round-trip from

$273
(Booking.com)

One-way from

$185
(Trip.com)

Popular in

June

Cheapest in

February

Average price

$493

Good round-trip deal

$762 or less

Good one-way deal

$287 or less
Provider with most accurate pricing for Toronto (YTO)-Seattle/Tacoma Intl flight deals.
Search Deals
Provider most trusted by Cheapflights users for Toronto (YTO)-Seattle/Tacoma Intl flights.
Search Deals
From Ontario to Seattle/Tacoma Intl
Search Deals
One-way flight from Ontario to Seattle/Tacoma Intl
Search Deals
Highest demand for flights based on searches. 13% potential increase in price ($54 potential increase over avg. RT price).
Search Deals
Cheapest flight prices on average. 3% potential price decrease ($14 potential savings vs. average RT price).
Search Deals
Average for round-trip flights in June 2026
Search Deals
Price to beat on a round-trip flight from Ontario to Seattle/Tacoma Intl.
Search Deals
Price to beat on a one-way flight from Ontario to Seattle/Tacoma Intl.
Search Deals

Cheapflights Fare Finder

 
Customize your flight search to find flights from Ontario to Seattle 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 2,558,603 searches. Data last updated June 29, 2026.
Use the filters below to find and compare flights from Ontario to Seattle that are best for you.

Fly from

Fly to

Route

Depart

Return

Price

Cheapest round-trip

TorontoSeattle

YYZ - SEA

YYZSEA

Toronto Pearson Intl

Fri 9/25

12:40 pm-6:45 pm

2 stops9h 05m

Seattle/Tacoma Intl

Sat 10/3

10:30 am-5:10 am

2 stops15h 40m

$334

LondonSeattle

YXU - SEA

YXUSEA

London

Wed 9/9

6:10 am-6:45 pm

1 stop15h 35m

Seattle/Tacoma Intl

Thu 9/10

7:35 pm-5:20 am

1 stop6h 45m

$347

TorontoSeattle

YKF - SEA

YKFSEA

Toronto Region of Waterloo Intl

Wed 9/16

8:40 pm-9:40 am

1 stop16h 00m

Seattle/Tacoma Intl

Thu 9/24

7:35 pm-7:50 pm

1 stop21h 15m

$369

TorontoSeattle

YKF - SEA

YKFSEA

Toronto Region of Waterloo Intl

Tue 9/22

8:40 pm-9:40 am

1 stop16h 00m

Seattle/Tacoma Intl

Mon 9/28

7:35 pm-7:50 pm

1 stop21h 15m

$369

TorontoSeattle

YKF - SEA

YKFSEA

Toronto Region of Waterloo Intl

Sat 9/19

8:40 pm-9:40 am

1 stop16h 00m

Seattle/Tacoma Intl

Sat 9/26

7:35 pm-7:50 pm

1 stop21h 15m

$369

HamiltonSeattle

YHM - SEA

YHMSEA

Hamilton

Sat 8/22

6:10 pm-9:40 am

1 stop18h 30m

Seattle/Tacoma Intl

Thu 9/3

7:00 am-5:15 pm

1 stop7h 15m

$373

HamiltonSeattle

YHM - SEA

YHMSEA

Hamilton

Wed 7/15

6:10 pm-9:40 am

1 stop18h 30m

Seattle/Tacoma Intl

Thu 7/23

7:00 am-5:15 pm

1 stop7h 15m

$373

HamiltonSeattle

YHM - SEA

YHMSEA

Hamilton

Wed 10/28

6:10 pm-2:20 pm

1 stop23h 10m

Seattle/Tacoma Intl

Sat 10/31

3:20 pm-5:17 pm

1 stop22h 57m

$378

TorontoSeattle

YYZ - SEA

YYZSEA

Toronto Pearson Intl

Tue 9/1

11:00 am-5:42 pm

2 stops9h 42m

Seattle/Tacoma Intl

Wed 9/9

11:03 am-9:32 pm

1 stop7h 29m

$390

MontrealSeattle

YUL - SEA

YULSEA

Montreal Pierre Elliott Trudeau Intl

Sat 8/22

12:47 pm-10:05 pm

1 stop12h 18m

Seattle/Tacoma Intl

Mon 8/31

9:10 am-11:52 pm

1 stop11h 42m

$392

Flights are sorted by cheapest round-trip flights first.

Deals found on 6/25

Showing 1-10 of 60 resultsSorted by cheapest first
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Best time to book a flight from Ontario to Seattle

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

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

Currently, January is the cheapest month in which you can book a flight from Region of Ontario to Seattle (average of $63). Flying from Region of Ontario to Seattle in June is currently the most expensive (average of $773). 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 SEA?

Find hourly flight availability from Ontario to Seattle. Discover flight options and departure times throughout the day, allowing you to choose a departure time that suits your schedule. Data last updated June 29, 2026.

Regardless of the time of day you decide to fly, the ticket price will remain around the same. Book flights from Region of Ontario to Seattle as you normally would.

Weekly flight availability from Region of Ontario to Seattle

Explore weekly flight availability from Ontario to Seattle. Discover flights operating on different days of the week, giving you the flexibility to choose a travel day that best fits your plans. Compare info to find the most convenient option for your journey. Data last updated June 29, 2026.

The most flights from CAON to SEA are scheduled on a Tuesday (4 on average). You will have fewer flight options on Wednesday, which is when the least amount of flights are scheduled (2 on average).

How much does it cost to fly round-trip from Region of Ontario to Seattle?

How far ahead should I book a flight from Region of Ontario to Seattle?

The price you pay for your flight from Region of Ontario to Seattle may vary depending on when you book. For the best chance of a lower fare, look to book 85 days in advance of your trip. Fares are likely to increase a fortnight or so before your departure date.

Related info for your journey

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

    Seattle/Tacoma Intl (SEA), located 11.4 mi from the city center, is the airport you fly into when you book flights from Ontario to Seattle.

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

    WestJet, United Airlines, and Delta can get you from Region of Ontario to Seattle in just under 9h 05m. Your travel time can differ by up to 3h 13m. Airlines will cover a distance of 2054 mi. Both multi-stop and nonstop flights can be found to your destination and back.

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

    $121 is the cheapest one-way deal found within the past few days, from Air Canada. You may also be able to find cheap deals on WestJet and Alaska Airlines, with prices starting from $127 and $127, respectively.

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

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

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

    No one likes to see their flight delayed. When booking a flight from Region of Ontario to Seattle consider choosing Hawaiian Airlines (100%), Alaska Airlines (95%) or Qatar Airways (67%) as they are the most reliable in getting you off to your destination on time.

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

    On average you can expect to pay $643 for a flight from Region of Ontario to Seattle. The cheapest flight overall is $205 while the most popular route, (Toronto Pearson Intl - Seattle/Tacoma Intl) is currently priced at $331.

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

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

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

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

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

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

    Currently, January is the cheapest month in which you can book a flight from Region of Ontario to Seattle (average of $63). Flying from Region of Ontario to Seattle in June is currently the most expensive (average of $773). 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

Traveling to a place near Seattle?

Book flights to Seattle if you plan to visit one of these locations
SeaTac
Tacoma
Lacey
Leavenworth
Olympia
Ocean Shores
Edmonds
Snoqualmie
Tumwater
Tukwila
Renton
Kent
Lynnwood
Ellensburg
Fife
Marysville
Lakewood
Issaquah
Shoreline
Centralia

Browse thousands of different options on Cheapflights for your next trip

Toggle through the tabs below to find thousands of options on Cheapflights for your next trip.

Top 6 airlines flying from Ontario to Seattle

Discover the top 6 airlines that operate flights from Ontario to Seattle. 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 2,558,603 searches. Data last updated June 29, 2026.
AirlineCheapestAverageFlexibilityOn-time
WestJetCheapest$194Average$381FlexibilityNo cancel feeOn-time60%
Alaska AirlinesCheapest$202Average$392FlexibilityNo cancel feeOn-time75%
Air CanadaCheapest$213Average$427FlexibilityNo cancel feeOn-time67%
United AirlinesCheapest$219Average$459FlexibilityNo cancel feeOn-time69%
American AirlinesCheapest$277Average$277FlexibilityNo cancel feeOn-time71%
DeltaCheapest$278Average$380FlexibilityNo cancel feeOn-timeN/A

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