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$309+ Cheap flights from Seattle (SEA) to London, ON (YXU)

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 9/10. Fares are subject to change and may not be available on all flights or dates of travel.
SEA — YXU
Jun 20 — Jun 271
Sat 6/20
Sat 6/27
1 adult, Economy
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Cheap flight deals from Seattle to London

Cheapest flights from Seattle to London
Explore the most affordable flight options available from Seattle to London. Find the lowest fares from popular airlines and budget airlines, with prices last updated on May 21, 2026.

This Trip.com deal was found by Cheapflights users on 5/17. 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 9/107:35 pm
SEA
-
YXU
1 stop6h 45m
WestJet
Sun 9/135:55 pm
YXU
-
SEA
1 stop18h 45m
WestJet
Deal found 5/17$309
This Trip.com deal was found by Cheapflights users on 5/18. 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.
Tue 9/227:35 pm
SEA
-
YXU
1 stop6h 45m
WestJet
Wed 10/76:10 am
YXU
-
SEA
1 stop15h 35m
WestJet
Deal found 5/18$313
This Trip.com deal was found by Cheapflights users on 5/18. 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.
Wed 9/910:30 am
SEA
-
YXU
1 stop15h 50m
WestJet
Wed 9/236:10 am
YXU
-
SEA
1 stop15h 35m
WestJet
Deal found 5/18$346
This WestJet deal was found by Cheapflights users on 5/19. 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 WestJet is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 9/87:35 pm
SEA
-
YXU
1 stop6h 45m
WestJet
Fri 9/115:55 pm
YXU
-
SEA
1 stop27h 50m
WestJet
Deal found 5/19$374
This Justfly.com deal was found by Cheapflights users on 5/17. 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 6/57:35 pm
SEA
-
YXU
1 stop6h 45m
WestJet
Sat 6/135:55 pm
YXU
-
SEA
1 stop18h 45m
WestJet
Deal found 5/17$447
This Kiwi.com deal was found by Cheapflights users on 5/18. 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 9/237:35 pm
SEA
-
YXU
1 stop6h 45m
Multiple Airlines
Wed 10/76:10 am
YXU
-
SEA
2 stops15h 23m
Multiple Airlines
Deal found 5/18$545
This Kiwi.com deal was found by Cheapflights users on 5/18. 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 9/97:35 pm
SEA
-
YXU
1 stop6h 45m
Multiple Airlines
Wed 9/236:10 am
YXU
-
SEA
2 stops14h 29m
Multiple Airlines
Deal found 5/18$548
This Air Canada deal was found by Cheapflights users on 5/18. 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 Air Canada is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 9/225:40 am
SEA
-
YXU
2 stops13h 00m
Air Canada
Wed 10/73:30 pm
YXU
-
SEA
1 stop8h 34m
Air Canada
Deal found 5/18$558

Find flight deals from Seattle to London

Discover tips and strategies to find the most affordable flight options for your journey from Seattle (SEA) to London (YXU). 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 May 21, 2026.

Most accurate provider

FlightHub
3 stars

Most trusted provider

FlightHub
3 stars

Round-trip from

$276
(Trip.com)
Provider with most accurate pricing for Seattle/Tacoma Intl-London flight deals.
Search Deals
Provider most trusted by Cheapflights users for Seattle/Tacoma Intl-London flights.
Search Deals
From Seattle/Tacoma Intl to London
Search Deals

Cheapflights Fare Finder

 
Customize your flight search to find flights from Seattle to London 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 May 21, 2026.
Use the filters below to find and compare flights from Seattle to London that are best for you.

Fly from

Fly to

Route

Depart

Return

Price

Cheapest round-trip

SeattleLondon

SEA - YXU

SEAYXU

Seattle/Tacoma Intl

Tue 9/8

7:35 pm-5:20 am

1 stop6h 45m

London

Fri 9/11

5:55 pm-6:45 pm

1 stop27h 50m

$374

SeattleLondon

SEA - YXU

SEAYXU

Seattle/Tacoma Intl

Thu 9/10

7:35 pm-5:20 am

1 stop6h 45m

London

Sun 9/13

2:40 pm-9:40 am

2 stops22h 00m

$479

SeattleLondon

SEA - YXU

SEAYXU

Seattle/Tacoma Intl

Wed 9/23

7:35 pm-5:20 am

1 stop6h 45m

London

Wed 10/7

6:10 am-6:33 pm

2 stops15h 23m

$545

SeattleLondon

SEA - YXU

SEAYXU

Seattle/Tacoma Intl

Wed 9/9

7:20 pm-9:20 am

2 stops11h 00m

London

Wed 9/23

10:05 am-6:32 pm

2 stops11h 27m

$558
Quickest round-trip

SeattleLondon

SEA - YXU

SEAYXU

Seattle/Tacoma Intl

Tue 9/8

7:20 pm-9:20 am

2 stops11h 00m

London

Fri 9/11

3:30 pm-9:04 pm

1 stop8h 34m

$571

Flights are sorted by cheapest round-trip flights first.

Deals found on 5/20

Sorted by cheapest first

Compare providers for flights from Seattle to London

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 Seattle to London in May.
ProviderPrice AccuracyTrust Score*
FlightHubPrice Accuracy3 starsTrust Score*3 stars
oojoPrice Accuracy3 starsTrust Score*2 stars
Trip.comPrice Accuracy1 starTrust Score*3 stars

*The Trust Score is based on feedback from users after their booking experience. It measures overall satisfaction, helping us identify issues like hidden fees, problems during the ticketing process, and the quality of customer service. This score is our best indicator of the provider's quality and reliability.

  • Most accurate provider: When it comes to deals on Seattle-London, Ontario flights, users find the pricing of FlightHub to be most consistent on Cheapflights vs. FlightHub Users can find the same prices on Seattle-London, Ontario flight deals on Cheapflights vs. FlightHub >95% of the time. Price accuracy is based on data collected from Seattle-London, Ontario flight searches over the past month and is updated monthly.
  • Most trusted provider: When it comes to deals on Seattle-London, Ontario 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 Seattle-London, Ontario 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 Seattle to London

Have a flexible travel schedule? Discover the best time to fly to London 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.

Related info for your journey

Find useful and relevant information for your journey from Seattle to London. Access travel guides, tips, and recommendations to enhance your travel experience. Get information about local attractions, weather, transportation options, and more.

  • How long is the flight from Seattle to London, Ontario?

    For as low as $374, WestJet can have you in London, Ontario from Seattle in 6h 45m. There are 2000 mi between Seattle and London, Ontario.

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

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

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

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

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

    Yes. Cheapflights offers flight deals from Seattle to London by cabin class. In addition to browsing deals, you can also filter by cabin class on the search results page after making a search.

See more FAQs

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