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$357+ Cheap flights from Seattle (SEA) to London, ON (YXU)

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.
SEA — YXU
Feb 19 — Feb 261
Thu 2/19
Thu 2/26
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 January 20, 2026.

This Kiwi.com deal was found by Cheapflights users on 1/19. 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 Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 3/53:10 pm
SEA
-
YXU
1 stop12h 25m
WestJet
Thu 3/128:10 pm
YXU
-
SEA
2 stops17h 15m
WestJet
Deal found 1/19$551
This Trip.com deal was found by Cheapflights users on 1/19. 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 Trip.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 3/53:10 pm
SEA
-
YXU
1 stop12h 25m
Multiple Airlines
Thu 3/128:10 pm
YXU
-
SEA
1 stop26h 47m
Multiple Airlines
Deal found 1/19$584
This Air Canada deal was found by Cheapflights users on 1/19. 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 Air Canada is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sun 4/58:00 pm
SEA
-
YXU
2 stops9h 43m
Air Canada
Sat 4/115:10 am
YXU
-
SEA
2 stops12h 53m
Air Canada
Deal found 1/19$618
This Air Canada deal was found by Cheapflights users on 1/17. 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 Air Canada is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 1/295:50 am
SEA
-
YXU
2 stops12h 31m
Air Canada
Sun 2/15:40 pm
YXU
-
SEA
1 stop7h 36m
Air Canada
Deal found 1/17$658
This FlightHub deal was found by Cheapflights users on 1/18. 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 FlightHub is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 1/211:30 pm
SEA
-
YXU
2 stops14h 04m
WestJet
Thu 1/228:10 pm
YXU
-
SEA
2 stops14h 27m
WestJet
Deal found 1/18$995

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 January 20, 2026.

Most accurate provider

oojo
3 stars

Most trusted provider

oojo
3 stars

Round-trip from

$551
(Kiwi.com)

One-way from

$357
(Air Canada)
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
One-way flight 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 January 20, 2026.
Use the filters below to find and compare flights from Seattle to London that are best for you.

Fly from

Seattle

Fly to

London

Route

Depart

Return

Price

SeattleLondon

SEA - YXU

SEAYXU

Seattle/Tacoma Intl

Thu 3/5

3:10 pm-6:35 am

1 stop12h 25m

London

Thu 3/12

8:10 pm-10:25 am

2 stops17h 15m

$551

SeattleLondon

SEA - YXU

SEAYXU

Seattle/Tacoma Intl

Thu 3/5

3:10 pm-6:35 am

1 stop12h 25m

London

Thu 3/12

8:10 pm-7:57 pm

1 stop26h 47m

$584

SeattleLondon

SEA - YXU

SEAYXU

Seattle/Tacoma Intl

Sun 4/5

8:00 pm-8:43 am

2 stops9h 43m

London

Sat 4/11

5:10 am-3:03 pm

2 stops12h 53m

$618

SeattleLondon

SEA - YXU

SEAYXU

Seattle/Tacoma Intl

Thu 6/18

11:30 am-9:37 pm

1 stop7h 07m

$357

SeattleLondon

SEA - YXU

SEAYXU

Seattle/Tacoma Intl

Thu 6/18

7:20 am-1:45 pm

3 stops27h 25m

$450

Flights are sorted by cheapest round-trip flights first.

Deals found on 1/19

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 January.
ProviderPrice AccuracyTrust Score*
FlightHubPrice Accuracy3 starsTrust Score*1 star
oojoPrice Accuracy3 starsTrust Score*3 stars
Trip.comPrice Accuracy2 starsTrust 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 oojo to be most consistent on Cheapflights vs. oojo Users can find the same prices on Seattle-London, Ontario flight deals on Cheapflights vs. oojo >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 oojo the most. oojo 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.

Cheapflights Insights

Everything you need to know about your flight from Seattle to London

What is the cheapest month to book a flight from Seattle to London, Ontario?

Currently, April is the cheapest month in which you can book a flight from Seattle to London, Ontario (average of $122). Flying from Seattle to London, Ontario in December is currently the most expensive (average of $281). 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.

Reviews of airlines servicing London

Get insights into the airlines that provide service to London. 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 London. Reviews last updated January 20, 2026.
Get a feel of what it's like to fly with Air Canada from Seattle to London by reading reviews from past customers. Users have also rated airlines in terms of entertainment options, comfort, food, crew/service, and boarding process.
Air Canada
7.1
Good
10,637 reviews

Overall

7.1

Food

6.3

Boarding

7.3

Comfort

7.1

Entertainment

6.8

Crew

7.8

Reviews

1 / 20
2.0
Mediocre

Sugith,Jan 2026

YYZ - YSB

8 am flight cancelled at 2 am. Rebooked next day. Had to pay to rebook myself on Porter to leave same day.
Air Canada
7.1
Good
10,637 reviews
Air Canada
7.1
Good
10,637 reviews

Overall

7.1

Food

6.3

Boarding

7.3

Comfort

7.1

Entertainment

6.8

Crew

7.8

Reviews

1 / 20
2.0
Mediocre

Sugith,Jan 2026

YYZ - YSB

8 am flight cancelled at 2 am. Rebooked next day. Had to pay to rebook myself on Porter to leave same day.

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 $618, WestJet can have you in London, Ontario from Seattle in 9h 43m. There are 2000 mi between Seattle and London, Ontario. This flight may include one or multiple stops.

  • What is the cheapest airline to fly from Seattle to London, Ontario round-trip?

    Cheapflights users have booked flights from Seattle to London, Ontario round-trip from $460.

  • 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.

  • What is the cheapest month to book a flight from Seattle to London, Ontario?

    Currently, April is the cheapest month in which you can book a flight from Seattle to London, Ontario (average of $122). Flying from Seattle to London, Ontario in December is currently the most expensive (average of $281). 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 London?

Book flights to London if you plan to visit one of these locations
Grand Bend

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Alternative routes for Seattle to London

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Top airline flying from Seattle to London

Discover the top airline that operate flights from Seattle to London. 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 January 20, 2026.
AirlineCheapestAverageFlexibilityOn-time
Air CanadaCheapest$460Average$857FlexibilityNo cancel feeOn-time67%

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