HomeSearch by dateVacation packagesHotelsFlight dealsCar rentalTravel tips & news
Seattle

$155+ 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 6/18. Fares are subject to change and may not be available on all flights or dates of travel.
YYZ — SEA
May 28 — Jun 41
Thu 5/28
Thu 6/4
1 adult, Economy
We work with more than 300 partners to bring you better travel deals

Find cheap flights from Ontario to Seattle 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 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 April 28, 2026.

This Kiwi.com deal was found by Cheapflights users on 4/25. 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.
Thu 7/1612:00 pm
YYZ
-
SEA
2 stops9h 45m
WestJet
Sat 8/17:35 pm
SEA
-
YYZ
1 stop8h 20m
WestJet
Deal found 4/25$226
This Kiwi.com deal was found by Cheapflights users on 4/25. 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.
Fri 8/211:30 pm
YYZ
-
SEA
1 stop8h 15m
WestJet
Mon 8/247:35 pm
SEA
-
YYZ
1 stop8h 20m
WestJet
Deal found 4/25$227
This Kiwi.com deal was found by Cheapflights users on 4/25. 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.
Fri 7/171:30 pm
YYZ
-
SEA
1 stop8h 15m
WestJet
Sat 8/110:30 am
SEA
-
YYZ
2 stops10h 29m
WestJet
Deal found 4/25$228
This Kiwi.com deal was found by Cheapflights users on 4/25. 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.
Wed 8/193:50 pm
YYZ
-
SEA
1 stop8h 10m
WestJet
Sun 8/237:35 pm
SEA
-
YYZ
1 stop8h 20m
WestJet
Deal found 4/25$229
This Trip.com deal was found by Cheapflights users on 4/26. 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 Trip.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 5/211:30 pm
YYZ
-
SEA
1 stop8h 15m
WestJet
Fri 6/57:35 pm
SEA
-
YYZ
1 stop8h 20m
WestJet
Deal found 4/26$230
This FlightHub deal was found by Cheapflights users on 4/28. 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 FlightHub is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 5/1912:00 pm
YYZ
-
SEA
1 stop9h 45m
WestJet
Tue 5/2610:30 am
SEA
-
YYZ
1 stop7h 45m
WestJet
Deal found 4/28$232
This Kiwi.com deal was found by Cheapflights users on 4/25. 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.
Wed 8/1212:00 pm
YYZ
-
SEA
1 stop9h 45m
WestJet
Wed 8/1910:30 am
SEA
-
YYZ
1 stop7h 45m
WestJet
Deal found 4/25$233
This Kiwi.com deal was found by Cheapflights users on 4/25. 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.
Fri 8/712:00 pm
YYZ
-
SEA
2 stops9h 45m
WestJet
Sat 8/2210:30 am
SEA
-
YYZ
1 stop9h 15m
WestJet
Deal found 4/25$234
This FlightHub deal was found by Cheapflights users on 4/28. 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 FlightHub is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 8/113:50 pm
YYZ
-
SEA
1 stop8h 10m
WestJet
Tue 8/187:35 pm
SEA
-
YYZ
1 stop7h 10m
WestJet
Deal found 4/28$235
This Kiwi.com deal was found by Cheapflights users on 4/25. 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.
Thu 8/61:30 pm
YYZ
-
SEA
1 stop8h 15m
WestJet
Tue 8/257:00 am
SEA
-
YYZ
1 stop8h 55m
WestJet
Deal found 4/25$236
This FlightHub deal was found by Cheapflights users on 4/27. 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 6/412:00 pm
YYZ
-
SEA
1 stop9h 45m
WestJet
Tue 6/237:00 am
SEA
-
YYZ
1 stop7h 10m
WestJet
Deal found 4/27$237
This Kiwi.com deal was found by Cheapflights users on 4/24. 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 7/2712:00 pm
YYZ
-
SEA
2 stops9h 45m
WestJet
Sat 8/297:35 pm
SEA
-
YYZ
1 stop7h 10m
WestJet
Deal found 4/24$238

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 April 28, 2026.

Most accurate provider

FlightHub
3 stars

Most trusted provider

FlightHub
3 stars

Round-trip from

$226
(Kiwi.com)

One-way from

$155
(Trip.com)

Popular in

June

Cheapest in

February

Average price

$404

Good round-trip deal

$417 or less

Good one-way deal

$244 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. 7% potential increase in price ($26 potential increase over avg. RT price).
Search Deals
Cheapest flight prices on average. 2% potential price decrease ($7 potential savings vs. average RT price).
Search Deals
Average for round-trip flights in April 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 April 28, 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

MontrealSeattle

YUL - SEA

YULSEA

Montreal Pierre Elliott Trudeau Intl

Thu 8/20

6:45 am-6:45 pm

2 stops15h 00m

Seattle/Tacoma Intl

Fri 8/28

7:35 pm-7:05 am

1 stop8h 30m

$265

MontrealSeattle

YUL - SEA

YULSEA

Montreal Pierre Elliott Trudeau Intl

Thu 7/16

6:45 am-6:45 pm

2 stops15h 00m

Seattle/Tacoma Intl

Sat 7/25

7:35 pm-7:05 am

1 stop8h 30m

$265

TorontoSeattle

YKF - SEA

YKFSEA

Toronto Region of Waterloo Intl

Wed 6/17

8:40 pm-9:00 pm

1 stop27h 20m

Seattle/Tacoma Intl

Tue 6/23

7:00 am-7:50 pm

1 stop9h 50m

$271

TorontoSeattle

YKF - SEA

YKFSEA

Toronto Region of Waterloo Intl

Fri 6/19

8:40 pm-9:40 am

1 stop16h 00m

Seattle/Tacoma Intl

Wed 6/24

7:00 am-7:50 pm

1 stop9h 50m

$273

MontrealSeattle

YUL - SEA

YULSEA

Montreal Pierre Elliott Trudeau Intl

Wed 8/5

8:00 pm-9:40 am

1 stop16h 40m

Seattle/Tacoma Intl

Mon 8/10

7:35 pm-7:05 am

1 stop8h 30m

$279

HamiltonSeattle

YHM - SEA

YHMSEA

Hamilton

Tue 6/23

6:10 pm-9:40 am

1 stop18h 30m

Seattle/Tacoma Intl

Tue 6/30

7:00 am-5:15 pm

1 stop7h 15m

$286

TorontoSeattle

YYZ - SEA

YYZSEA

Toronto Pearson Intl

Thu 5/28

2:20 pm-10:48 pm

1 stop11h 28m

Seattle/Tacoma Intl

Sat 6/6

9:35 am-10:59 pm

1 stop10h 24m

$288

HamiltonSeattle

YHM - SEA

YHMSEA

Hamilton

Fri 5/22

6:10 pm-9:40 am

1 stop18h 30m

Seattle/Tacoma Intl

Wed 8/19

7:00 am-5:15 pm

1 stop7h 15m

$288

TorontoSeattle

YYZ - SEA

YYZSEA

Toronto Pearson Intl

Sat 6/6

6:30 am-11:19 pm

1 stop19h 49m

Seattle/Tacoma Intl

Mon 6/8

11:52 pm-9:54 am

1 stop7h 02m

$289

LondonSeattle

YXU - SEA

YXUSEA

London

Thu 6/11

5:55 pm-6:45 pm

1 stop27h 50m

Seattle/Tacoma Intl

Thu 6/18

7:35 pm-5:20 am

1 stop6h 45m

$294

Flights are sorted by cheapest round-trip flights first.

Deals found on 4/26

Showing 1-10 of 60 resultsSorted by cheapest first
1
2
3
...
6

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

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.

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 July is currently the most expensive (average of $798). 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 April 28, 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.

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

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, Delta, and United Airlines can get you from Region of Ontario to Seattle in just under 11h 28m. Your travel time can differ by up to 8h 21m. 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?

    $100 is the cheapest one-way deal found within the past few days, from WestJet. You may also be able to find cheap deals on Air Canada and Alaska Airlines, with prices starting from $121 and $128, 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, Hamilton - 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 Air Tahiti Nui (93%), Alaska Airlines (70%) or Hawaiian Airlines (70%) 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 $443 for a flight from Region of Ontario to Seattle. The cheapest flight overall is $171 while the most popular route, (Toronto Pearson Intl - Seattle/Tacoma Intl) is currently priced at $276.

  • 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 July is currently the most expensive (average of $798). 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
Ocean Shores
Olympia
Lynnwood
Lacey
Edmonds
Leavenworth
Snoqualmie
Tumwater
Tukwila
Puyallup
Kent
Renton
Kirkland
Ellensburg
Fife
Lakewood
Issaquah
Shoreline

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 April 28, 2026.
AirlineCheapestAverageFlexibilityOn-time
WestJetCheapest$192Average$370FlexibilityNo cancel feeOn-time60%
Alaska AirlinesCheapest$202Average$389FlexibilityNo cancel feeOn-time75%
Air CanadaCheapest$213Average$429FlexibilityNo cancel feeOn-time67%
United AirlinesCheapest$238Average$424FlexibilityNo cancel feeOn-time69%
American AirlinesCheapest$277Average$277FlexibilityNo cancel feeOn-time71%
DeltaCheapest$278Average$373FlexibilityNo cancel feeOn-timeN/A

100% Free

Cheapflights is completely free to use, so you can start saving the moment you arrive.

Book with Flexibility

Our users can plan ahead with confidence and find flights with no change fees

Travel Smart

Millions of people come to us for their flight needs every year. We help make travel planning easy by providing useful insights and data-driven graphs that can inform your decisions.