Cheap Flights from Ontario to Seattle starting at S$ 57

Here are our top budget-friendly flights, offering flexible one-way or round-trip options. Additional flights with other timings and airlines are also available.

Round-trip
One way

Crossed out prices are calculated based on the average price of the corresponding route on Trip.com.

Cheapest time to fly from Ontario to Seattle

We monitor flight fares to help you find the best deals effortlessly

Cheapest flights

From price

11 18
18 25
Jun

25 1
1 8
8 15
15 22
22 29
Jul

29 6
6 13
13 20
20 27
Aug

27 3

Displayed prices are calculated based on the lowest average weekly prices of the corresponding route on Trip.com.

Frequently Asked Questions

When to buy flight tickets from Ontario (ONT) to Seattle (SEA) the cheapest?

Airlines adjust prices for flights from Ontario to Seattle based on the date and time of your booking. By analyzing data from all airlines, on Trip.com, you can find the cheapest flight prices on Tuesdays, Wednesdays, and Saturdays.
How much is a flight from Ontario (ONT) to Seattle (SEA) cost?

According to Trip.com's data, the lowest price is around S$ 238.
How many airports in Seattle?

There are 3 airports near Seattle: Seattle–Tacoma International Airport, King County (Boeing Field) International Airport and Lake Union Sea Plane Base.

How to find a cheap flight from Ontario to Seattle

Wait until the last minute and flight costs are often sky-high. Plan ahead, book the right way, and your savings can soar. We have loads of saving tips to help you find a cheap flight from Ontario to Seattle. Book your flights at the right time and save more.

Choose your dates flexibly and get the best deals on flights from Ontario to Seattle.

Tap 'Date' on the flight search bar to browse the calendar for Ontario to Seattle airfare over the next 6 months in 2025. If you're looking to fly within the next 3 months, the cheapest date seems to be Wed, Jun 4, with one-way flights starting at S$ 57.

Compare cheap flight deals from hundreds of airlines for Ontario to Seattle flights.

Our extensive search lets you compare prices from over 500 airlines to find the cheapest flights from Ontario to Seattle. The cheapest flight at the moment is with Frontier Airlines.

Set up a Price Alert

Set up a Price Alert for your Ontario to Seattle flights and track ticket prices easily—no need for daily checks.

Don't miss out on cheap deals and promo codes for Ontario to Seattle flights.

You can always get the latest deals through Trip.com Deals and Promo Codes for cheap flights. Sign up for a free membership for more exclusive flight deals.

Book early or wait for last-minute deals.

It's always better to book early. Flight tickets are often at their lowest when first released, usually a year ahead of departure. Keep an eye out as soon as your desired flights open for booking. If you miss the early deals, you may still find lower prices closer to your travel date.

Search for flights on the go.

For the best flight booking experience on the go, download Trip.com and search for cheap flights from Ontario to Seattle to get your exclusive deals.

Flying from Ontario to Seattle

Cheapest one-way flight price	S$ 56
Cheapest return ticket price	S$ 91
Off-season for travel	March
Peak season for travel	February
Flight distance	12,362.98km
Popular airline	Alaska Airlines