Ontario to Seattle flights
The cheapest round trip we found from Ontario to Seattle is $208 (Dec 28 – Jan 4, 2027, 1 stop), 8% below the usual $225.
ONT to SEA · Round trip · Economy · Prices per person in USD · Price found (45 minutes ago)
Cheapest found
Cheapest round trip by month
Lowest fare found per departure month| Month | Cheapest round trip |
|---|---|
| November 2026 | $256 |
| December 2026 | $193 (cheapest month) |
| January 2027 | $219 |
Cheapest dates in the next 4 months
Round trip, per person-
Dec 28 – Jan 4, 2027 7 nights · leave Mon$208 −8% vs usual$208 −8% vs usual Book
Frontier Airlines 1 stop · 4h 06m -
Jan 1 – 9, 2027 8 nights · leave Fri$219$219 Book
Alaska Airlines Nonstop · 2h 52m -
Jan 15 – 18, 2027 3 nights · leave Fri$226$226 Book
Frontier Airlines 1 stop · 5h 36m
-
Nov 25 – 27 2 nights · leave Wed$260 +16% vs usual$260 +16% vs usual Book
Frontier Airlines 1 stop · 4h 06m
-
Dec 20 – 26 6 nights · leave Sun$261 +16% vs usual$261 +16% vs usual Book
Frontier Airlines 1 stop · 4h 03m
-
Nov 12 – 17 5 nights · leave Thu$334 +48% vs usual$334 +48% vs usual Book
Frontier Airlines Nonstop · 3h 02m
-
Nov 26 – 29 3 nights · leave Thu$336 +49% vs usual$336 +49% vs usual Book
Frontier Airlines 1 stop · 5h 29m
Prices change often. The booking site shows the final price before you pay. Other dates? Set an alert
Things to do in Seattle
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Airport transfer to Seattle
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Plan the rest of your trip
Seattle · Dec 28 – Jan 4, 2027Partner links: we may earn a commission if you book, at no extra cost to you.
Good to know
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Flights to Seattle from other cities
All flights to Seattle Flying the other way? Seattle to Ontario from $179
Ontario to Seattle: questions
How much does a flight from Ontario to Seattle cost?
The cheapest round trip we have found right now is $208, leaving December 28 and returning January 4. The usual price on this route is about $225, so this fare is 8% less. Prices are per person, economy, in USD.
What is the cheapest month to fly from Ontario to Seattle?
December 2026, with round trips from $193. The most expensive month in our data is November (from $256). Based on the 3 months ahead we have prices for.
Which airports do Ontario to Seattle flights use?
Ontario airports include Ontario International (ONT). Seattle airports include Seattle-Tacoma International (SEA) and Boeing Field International (BFI). The prices on this page cover every airport in both cities (ONT and SEA are the city codes).
About this route
We track round-trip economy fares from Ontario (United States) to Seattle (United States) using Travelpayouts / Aviasales data. The cheapest round trip we've found is $208, departing December 28 and returning January 4, about 8% below the usual $225. Right now we're following 7 upcoming date combinations on this route. The cheapest month to fly in our data is December, from $193. Prices are per person and were correct when found; the final price is set by the airline or booking site when you book.