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Cheap flights from London, ON to Seattle from C$ 321

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 12/12. Fares are subject to change and may not be available on all flights or dates of travel.
YXU — SEA
28 Nov — 5 Dec1
1 adult
1 adult, Economy, 0 bags

Find flight deals from London to Seattle

Enter your travel dates to find the best prices.

Cheapest flights from London to Seattle
Explore the most affordable flight options available from London to Seattle. Find the lowest fares from popular airlines and budget airlines, with prices last updated on 29 October 2025.

Thu 11/128:10 p.m.YXU - SEA
1 stop21h 10mWestJet
Thu 18/123:10 p.m.SEA - YXU
1 stop12h 24mWestJet
Deal found 27/10C$ 824
Mon 10/115:40 p.m.YXU - SEA
1 stop7h 36mUnited Airlines
Fri 14/117:13 p.m.SEA - YXU
2 stops18h 52mUnited Airlines
Deal found 28/10C$ 1,019
Thu 11/129:25 a.m.YXU - SEA
2 stops16h 03mUnited Airlines
Thu 18/1212:35 p.m.SEA - YXU
3 stops25h 30mUnited Airlines
Deal found 27/10C$ 1,087
Mon 10/115:40 p.m.YXU - SEA
1 stop7h 36mAir Canada
Fri 14/118:10 a.m.SEA - YXU
1 stop10h 11mAir Canada
Deal found 28/10C$ 1,238

Cheap flight deals from London to Seattle

Discover tips and strategies to find the most affordable flight options for your journey from London (YXU) to Seattle (SEA). 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 29 October 2025.

Round-trip from

C$ 824

One-way from

C$ 321
WestJet
  • WestJet
  • 11/12-18/12
  • 2 total stops
  • 33h 34m total
  • London to Seattle
Search Deals
12/12
  • 12/12
  • 2 total stops
  • 14h 25m total
  • London to Seattle
Search Deals

Cheapflights Fare Finder

 
Customize your flight search to find flights from London 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 629,999 searches. Data last updated 29 October 2025.
Use the filters below to find and compare flights from London to Seattle that are best for you.

Fly from

London

Fly to

Seattle

Route

Depart

Return

Price

LondonSeattle

YXU - SEA

YXUSEA

London

Thu 11/12

8:10 p.m.-2:20 p.m.

1 stop21h 10m

Seattle/Tacoma Intl

Thu 18/12

3:10 p.m.-6:34 a.m.

1 stop12h 24m

C$ 824

LondonSeattle

YXU - SEA

YXUSEA

London

Mon 10/11

5:40 p.m.-10:16 p.m.

1 stop7h 36m

Seattle/Tacoma Intl

Fri 14/11

7:13 p.m.-5:05 p.m.

2 stops18h 52m

C$ 1,019

LondonSeattle

YXU - SEA

YXUSEA

London

Thu 11/12

9:25 a.m.-10:28 p.m.

2 stops16h 03m

Seattle/Tacoma Intl

Thu 18/12

12:35 p.m.-5:05 p.m.

3 stops25h 30m

C$ 1,087

LondonSeattle

YXU - SEA

YXUSEA

London

Mon 10/11

5:40 p.m.-10:16 p.m.

1 stop7h 36m

Seattle/Tacoma Intl

Fri 14/11

8:10 a.m.-9:21 p.m.

1 stop10h 11m

C$ 1,238

LondonSeattle

YXU - SEA

YXUSEA

London

Fri 12/12

7:30 a.m.-6:55 p.m.

2 stops14h 25m

C$ 321

LondonSeattle

YXU - SEA

YXUSEA

London

Fri 12/12

5:40 p.m.-10:16 p.m.

1 stop7h 36m

C$ 344

LondonSeattle

YXU - SEA

YXUSEA

London

Fri 12/12

7:30 a.m.-10:22 a.m.

3 stops29h 52m

C$ 381

Flights are sorted by cheapest round-trip flights first.

Deals found on 28/10

Best time to book a flight from London to Seattle

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

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

Currently, May is the cheapest month in which you can book a flight from London, Ontario to Seattle (average of C$ 129). Flying from London, Ontario to Seattle in June is currently the most expensive (average of C$ 348). 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 YXU to SEA?

Find hourly flight availability from London 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 29 October 2025.

One of the essential ways to save on airfare from London, Ontario to Seattle is to remain as flexible as possible. Flights that are at noon tend to be the most expensive. A flight in the evening could potentially save you up to 33% on airfare.

Reviews of airlines servicing Seattle

Get insights into the airlines that provide service to Seattle. 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 Seattle. Reviews last updated 29 October 2025.
Read through reviews of airlines operating flights from London to Seattle, such as United Airlines,WestJet, andAir Canada. Reviews also offer insight into each airline's entertainment options, comfort, food, crew/service, and boarding process.
United Airlines
7.4
Good
8,999 reviews
Check prices

Comfort

7.3

Overall

7.4

Food

6.6

Crew

8.1

Entertainment

7.1

Boarding

7.7

Reviews

1 / 20
2.0
Mediocre

Sebrena,Oct 2025

IAH - RSW

The worst that I have ever experienced in my life so bad if it was free I'm not ever going to use your Airline again I dont believe ..... very disappointed 😞 😔0000000000000
United Airlines
7.4
Good
8,999 reviews
United Airlines
7.4
Good
8,999 reviews
Check prices

Comfort

7.3

Overall

7.4

Food

6.6

Crew

8.1

Entertainment

7.1

Boarding

7.7

Reviews

1 / 20
2.0
Mediocre

Sebrena,Oct 2025

IAH - RSW

The worst that I have ever experienced in my life so bad if it was free I'm not ever going to use your Airline again I dont believe ..... very disappointed 😞 😔0000000000000
WestJet
7.2
Good
3,148 reviews
United Airlines
7.4
Good
8,999 reviews
Check prices

Comfort

7.3

Overall

7.4

Food

6.6

Crew

8.1

Entertainment

7.1

Boarding

7.7

Reviews

1 / 20
2.0
Mediocre

Sebrena,Oct 2025

IAH - RSW

The worst that I have ever experienced in my life so bad if it was free I'm not ever going to use your Airline again I dont believe ..... very disappointed 😞 😔0000000000000
Air Canada
7.1
Good
10,372 reviews
United Airlines
7.4
Good
8,999 reviews
Check prices

Comfort

7.3

Overall

7.4

Food

6.6

Crew

8.1

Entertainment

7.1

Boarding

7.7

Reviews

1 / 20
2.0
Mediocre

Sebrena,Oct 2025

IAH - RSW

The worst that I have ever experienced in my life so bad if it was free I'm not ever going to use your Airline again I dont believe ..... very disappointed 😞 😔0000000000000

Related info for your journey

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

    Departing from London, Ontario to Seattle will take you 7h 36m. The distance between London, Ontario and Seattle is about 3219 km. When browsing for deals, the options you’ll see will be for both direct flights and flights with stops.

  • What are the cheapest airlines flying from London, Ontario to Seattle round-trip?

    According to our current data, WestJet (C$ 243), United Airlines (C$ 281), and Air Canada (C$ 373) offers the cheapest pricing from London, Ontario to Seattle.

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

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

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

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

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

    Yes. Cheapflights offers flight deals from London 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 London, Ontario to Seattle?

    Currently, May is the cheapest month in which you can book a flight from London, Ontario to Seattle (average of C$ 129). Flying from London, Ontario to Seattle in June is currently the most expensive (average of C$ 348). 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

Travelling to a place near Seattle?

Book flights to Seattle if you plan to visit one of these locations
Leavenworth
SeaTac
Tukwila
Tacoma
Mukilteo
Bothell
Cashmere
Olympia
Renton
Marysville
Lynnwood

Browse thousands of different options on Cheapflights for your next trip

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Alternative routes for London to Seattle

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Top 3 airlines flying from London to Seattle

Discover the top 3 airlines that operate flights from London 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 629,999 searches. Data last updated 29 October 2025.
AirlineCheapestAverageFlexibilityOn-time
WestJetCheapestC$ 243AverageC$ 420FlexibilityNo cancel feeOn-time60%
Search WestJet flights
United AirlinesCheapestC$ 281AverageC$ 298FlexibilityNo cancel feeOn-time69%
Search United Airlines flights
Air CanadaCheapestC$ 373AverageC$ 456FlexibilityNo cancel feeOn-time67%
Search Air Canada 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 London to Seattle?

900+ travel sites are searched through when a user searches for a flight using Cheapflights. From the search interface, users can use filters to choose airlines, airports, flight times, cabin classes and more to their preference. Book your flight to Seattle from London today with Cheapflights!

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

Cheapflights helps you find that perfect flight to Seattle from London by searching from hundreds of airlines and agencies you know and love. We are also free to use, in case you were wondering!

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

Certainly. Search results for flights to Seattle from London shown to you on Cheapflights can be narrowed down with different useful search filters, which includes flexible booking options.

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

Yes, Cheapflights offers price alerts on London to Seattle flights so you can book your travel at the perfect time. Price Alerts can be enabled by clicking the bell icon next to the flight deals above and providing your email address where you want to receive the alerts.

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