฿3,550 Cheap Flights from Ontario (ONT) to Seattle (SEA)

View ฿3,550 flight on Tue, 30 Sep 2025Opens in a new window

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

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

Prices were available within the past 7 days and start at ฿3,550 for one-way flights and ฿6,115 for round trip, for the period specified. Prices and availability are subject to change. Additional terms apply.

Delta
Sat, 25 Oct - Mon, 27 Oct
ONT
Ontario
SEA
Seattle
฿6,115 Return, found 6 days ago
฿6,115
Return
found 6 days ago
Select Delta flight, departing Sat, 25 Oct from Ontario to Seattle, returning Mon, 27 Oct, priced at ฿6,115 found 6 days ago
United
Sat, 25 Oct - Mon, 27 Oct
ONT
Ontario
SEA
Seattle
฿7,900 Return, found 6 days ago
฿7,900
Return
found 6 days ago
Select United flight, departing Sat, 25 Oct from Ontario to Seattle, returning Mon, 27 Oct, priced at ฿7,900 found 6 days ago
Delta
Sat, 25 Oct - Mon, 27 Oct
ONT
Ontario
SEA
Seattle
฿8,070 Return, found 6 days ago
฿8,070
Return
found 6 days ago
Select Delta flight, departing Sat, 25 Oct from Ontario to Seattle, returning Mon, 27 Oct, priced at ฿8,070 found 6 days ago
Delta
Sat, 25 Oct - Mon, 27 Oct
ONT
Ontario
SEA
Seattle
฿8,230 Return, found 6 days ago
฿8,230
Return
found 6 days ago
Select Delta flight, departing Sat, 25 Oct from Ontario to Seattle, returning Mon, 27 Oct, priced at ฿8,230 found 6 days ago
Delta
Sat, 25 Oct - Mon, 27 Oct
ONT
Ontario
SEA
Seattle
฿8,400 Return, found 6 days ago
฿8,400
Return
found 6 days ago
Select Delta flight, departing Sat, 25 Oct from Ontario to Seattle, returning Mon, 27 Oct, priced at ฿8,400 found 6 days ago
Delta
Sat, 25 Oct - Mon, 27 Oct
ONT
Ontario
SEA
Seattle
฿8,555 Return, found 6 days ago
฿8,555
Return
found 6 days ago
Select Delta flight, departing Sat, 25 Oct from Ontario to Seattle, returning Mon, 27 Oct, priced at ฿8,555 found 6 days ago
American Airlines
Sat, 25 Oct - Mon, 27 Oct
ONT
Ontario
SEA
Seattle
฿8,880 Return, found 6 days ago
฿8,880
Return
found 6 days ago
Select American Airlines flight, departing Sat, 25 Oct from Ontario to Seattle, returning Mon, 27 Oct, priced at ฿8,880 found 6 days ago
Delta
Sat, 25 Oct - Mon, 27 Oct
ONT
Ontario
SEA
Seattle
฿8,885 Return, found 6 days ago
฿8,885
Return
found 6 days ago
Select Delta flight, departing Sat, 25 Oct from Ontario to Seattle, returning Mon, 27 Oct, priced at ฿8,885 found 6 days ago
American Airlines
Sat, 25 Oct - Mon, 27 Oct
ONT
Ontario
SEA
Seattle
฿9,040 Return, found 6 days ago
฿9,040
Return
found 6 days ago
Select American Airlines flight, departing Sat, 25 Oct from Ontario to Seattle, returning Mon, 27 Oct, priced at ฿9,040 found 6 days ago
United
Sat, 25 Oct - Mon, 27 Oct
ONT
Ontario
SEA
Seattle
฿9,045 Return, found 6 days ago
฿9,045
Return
found 6 days ago
Select United flight, departing Sat, 25 Oct from Ontario to Seattle, returning Mon, 27 Oct, priced at ฿9,045 found 6 days ago

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

October is typically the cheapest month to fly

From ฿2,116 - ฿5,095 per traveller.

Graph displaying average flight prices per month

Flight from Ontario to Seattle route information
Origin airport
Los Angeles - Ontario Intl.
Destination airport
Seattle - Tacoma Intl.
Return price
฿6,115
Distance
1530 km
Average flight time
2 hours 44 mins

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 Seattle, 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 ฿3,550 and roundtrip prices from ฿6,115. 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 Seattle 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 ONT to SEA travel arrangements today and embark on the journey of a lifetime in Seattle.

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 ฿6,115. 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.

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