฿2,540 Cheap Flights from Ontario (ONT) to Seattle (SEA)

View ฿2,540 flight on Fri, 27 Feb 2026Opens in a new window

Popular airlines from Los Angeles - Ontario Intl. Airport (ONT) to Seattle

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Cheap Flights from Ontario (ONT) to Seattle (SEA)

Prices were available within the past 7 days and start at ฿2,540 for one-way flights and ฿3,170 for round trip, for the period specified. Prices and availability are subject to change. Additional terms apply.

Delta
Tue, 10 Mar - Mon, 23 Mar
ONT
Ontario
SEA
Seattle
฿3,170 Return, found 3 days ago
฿3,170
Return
found 3 days ago
Select Delta flight, departing Tue, 10 Mar from Ontario to Seattle, returning Mon, 23 Mar, priced at ฿3,170 found 3 days ago
Delta
Thu, 12 Mar - Mon, 16 Mar
ONT
Ontario
SEA
Seattle
฿3,810 Return, found 5 days ago
฿3,810
Return
found 5 days ago
Select Delta flight, departing Thu, 12 Mar from Ontario to Seattle, returning Mon, 16 Mar, priced at ฿3,810 found 5 days ago
Delta
Fri, 27 Feb - Wed, 4 Mar
ONT
Ontario
SEA
Seattle
฿4,125 Return, found 6 days ago
฿4,125
Return
found 6 days ago
Select Delta flight, departing Fri, 27 Feb from Ontario to Seattle, returning Wed, 4 Mar, priced at ฿4,125 found 6 days ago
Delta
Fri, 27 Feb - Wed, 4 Mar
ONT
Ontario
SEA
Seattle
฿4,440 Return, found 6 days ago
฿4,440
Return
found 6 days ago
Select Delta flight, departing Fri, 27 Feb from Ontario to Seattle, returning Wed, 4 Mar, priced at ฿4,440 found 6 days ago
Delta
Tue, 10 Mar - Fri, 13 Mar
ONT
Ontario
SEA
Seattle
฿4,445 Return, found 3 days ago
฿4,445
Return
found 3 days ago
Select Delta flight, departing Tue, 10 Mar from Ontario to Seattle, returning Fri, 13 Mar, priced at ฿4,445 found 3 days ago
Delta
Thu, 12 Mar - Fri, 20 Mar
ONT
Ontario
SEA
Seattle
฿5,075 Return, found 5 days ago
฿5,075
Return
found 5 days ago
Select Delta flight, departing Thu, 12 Mar from Ontario to Seattle, returning Fri, 20 Mar, priced at ฿5,075 found 5 days ago
Delta
Fri, 27 Feb - Wed, 4 Mar
ONT
Ontario
SEA
Seattle
฿5,390 Return, found 6 days ago
฿5,390
Return
found 6 days ago
Select Delta flight, departing Fri, 27 Feb from Ontario to Seattle, returning Wed, 4 Mar, priced at ฿5,390 found 6 days ago
United
Fri, 27 Feb - Wed, 4 Mar
ONT
Ontario
SEA
Seattle
฿7,405 Return, found 6 days ago
฿7,405
Return
found 6 days ago
Select United flight, departing Fri, 27 Feb from Ontario to Seattle, returning Wed, 4 Mar, priced at ฿7,405 found 6 days ago
Alaska Airlines
Sun, 22 Feb - Sat, 7 Mar
ONT
Ontario
SEA
Seattle
฿8,060 Return, found 3 days ago
฿8,060
Return
found 3 days ago
Select Alaska Airlines flight, departing Sun, 22 Feb from Ontario to Seattle, returning Sat, 7 Mar, priced at ฿8,060 found 3 days ago
American Airlines
Fri, 27 Feb - Wed, 4 Mar
ONT
Ontario
SEA
Seattle
฿9,640 Return, found 6 days ago
฿9,640
Return
found 6 days ago
Select American Airlines flight, departing Fri, 27 Feb from Ontario to Seattle, returning Wed, 4 Mar, priced at ฿9,640 found 6 days ago

Find the cheapest month to fly from Ontario (ONT) to Seattle (SEA)

November is typically the cheapest month to fly

From ฿2,528 - ฿6,851 per traveller.

Frequently asked questions

How much is a flight from Ontario Airport to Sea-Tac Airport?
If you're travelling between Ontario Airport and Seattle - Tacoma Intl. Airport (SEA), round-trip journeys start from ฿3,170. This figure is based on fares quoted within the last 7 days on Expedia for flights departing within the next year, so don't hang about. Book now and save yourself both money and time. Prices and availability are subject to change. Additional terms apply.
Do I need to pay a cancellation fee if I cancel my flight from Los Angeles - Ontario Intl. Airport (ONT) to Sea-Tac Airport?
We understand that things come up unexpectedly, so we've made it as simple as possible for you to cancel your trip online. Just visit the Customer Service Portal and follow the instructions.
How do I find cheap flights from Ontario Airport to Seattle - Tacoma Intl. Airport (SEA) that have flexible change policies?
Many airlines offer the option to reschedule your flight without a change fee. All you pay is the difference between the original flight and the new flight. When you're searching for Los Angeles - Ontario Intl. Airport (ONT) to Seattle - Tacoma Intl. Airport (SEA) flights, you'll see a "no change fees" filter for you to select.
How far is the flight from Los Angeles - Ontario Intl. Airport (ONT) to SEA?
The flight distance from Los Angeles - Ontario Intl. Airport (ONT) to Sea-Tac Airport is 1,550 kilometres. Pack yourself a drink, some snacks and an interesting novel to read. Keep yourself busy in the air and time will zip by.
Which airlines fly direct from Los Angeles - Ontario Intl. Airport (ONT) to Seattle - Tacoma Intl. Airport (SEA)?
Many travellers choose to fly with Alaska Airlines (AS) from Ontario Airport to Seattle - Tacoma Intl. Airport (SEA). This leading airline offers 117 flights monthly, so you can easily find a flight time that works for you. Another carrier operating on this route is Delta Air Lines (DL). You'll have 86 flights every month to choose from.
Are Ontario Airport to Seattle - Tacoma Intl. Airport (SEA) flight tickets cheaper when they're purchased at the last minute?
Last-minute planners can sometimes pick up a bargain, with some super cheap airfares from ONT to Sea-Tac Airport popping up a few weeks prior to the departure date. If you'd rather book ahead of time, Expedia compares and updates all the best flight deals regularly — as early as a year in advance in some cases. It does depend on the carrier though, as not all airlines release prices so far in advance.

Travel information

Origin airport
Los Angeles - Ontario Intl.
Destination airport
Seattle - Tacoma Intl.
Return price
฿3,170
Distance
1530 km
Average flight time
2 hours 56 mins

Book with confidence

Perfect flights from Ontario to Seattle

Embark on an unforgettable journey without breaking the bank with Expedia's incredible deals on cheap flights from Ontario to Seattle. Whether you're aching for a romantic escape with your partner, craving an adventurous solo expedition, or yearning to immerse yourself in the local history and culture, we've got you covered.
 
Picture yourself strolling through the streets of , surrounded by breathtaking architecture and absorbing the vibrant atmosphere of this captivating city. Indulge in the mouth-watering local specialties, from tantalizing street food to exquisite fine dining. With Expedia, you can experience all of this and more, without sacrificing your budget.
 
Our flexible Los Angeles - Ontario Intl. to Seattle - Tacoma Intl. ticket options cater to your travel preferences, with incredible one-way fares from ฿2,540 and roundtrip prices from ฿3,170. Whether you're planning a short city break or a longer adventure, our dynamic pricing ensures that you find the best deals for your journey.
 
But the magic doesn't stop there. Expedia offers a range of partner services to enhance your trip. Rent a car at Seattle - Tacoma Intl. and explore and its surrounding areas at your own pace. Discover hidden gems off the beaten path, and create unforgettable memories. We also provide a handpicked selection of accommodations, from charming bed and breakfasts to luxury hotels, ensuring that you have a comfortable and memorable stay.
 
Planning your next great adventure is a breeze with Expedia. Our user-friendly platform, unbeatable prices, and round-the-clock customer support are designed to make your travel experience seamless and stress-free. So, why wait? Book your to travel arrangements today and embark on the journey of a lifetime in Seattle.
Perfect flights from Ontario to Seattle
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