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Uncover the best deals on Ontario to Seattle flights by comparing fares from hundreds of airlines and agencies.
Good to Know: Cheapest and Fastest ONT - SEA Flights
Useful information for finding best airline tickets from Ontario International to Seattle Tacoma International on your next trip.
Cheapest Round Trip Flight
$549
Southwest Airlines
• nonstop
• 7h 15m
Nov 20 – Nov 28
The cheapest round trip flight from Ontario to Seattle (ONT-SEA-ONT) is currently $549
Cheapest One way Flight
$140
Southwest Airlines
• 1 stop
• 13h 45m
Oct 25
The cheapest one way flight from Ontario to Seattle (ONT-SEA) is currently $140
Cheapest Direct Flight
$549
Southwest Airlines
• nonstop
• 7h 15m
Nov 20
The cheapest nonstop flight from Ontario to Seattle (ONT-SEA) is currently $549
Fastest Flight
4h 5m
The fastest nonstop flight from Ontario to Seattle (ONT-SEA) takes 4h 5m
Top Airlines Flying from Ontario to Seattle
Latest Flight Deals from Ontario (ONT) to Seattle (SEA)
Compare and book low fare round-trip air tickets from Ontario to Seattle. Ideal for travelers with confirmed return itineraries.
Nov 20 - Nov 28, Economy
Ontario → Seattle
7h 15m
8:45 PM - 1:20 AM • nonstop
Ontario → Seattle
4h 5m
10:30 AM - 1:15 PM • nonstop
Southwest Airlines
Nov 20 - Nov 28, Economy
Ontario → Seattle
17h 5m
8:40 PM - 7:05 AM • 1 stop
Ontario → Seattle
12h 20m
10:30 AM - 6:10 PM • 2 stops
Southwest Airlines
Nov 20 - Nov 28, Economy
Ontario → Seattle
20h 35m
12:10 PM - 12:45 AM • 1 stop
Ontario → Seattle
20h 10m
7:50 PM - 8:00 AM • 1 stop
Southwest Airlines
Nov 20 - Nov 28, Economy
Ontario → Seattle
13h 55m
1:35 PM - 10:10 PM • 1 stop
Ontario → Seattle
20h 10m
7:50 PM - 8:00 AM • 1 stop
Southwest Airlines
Nov 20 - Nov 28, Economy
Ontario → Seattle
17h 25m
11:25 AM - 10:10 PM • 1 stop
Ontario → Seattle
20h 10m
7:50 PM - 8:00 AM • 1 stop
Southwest Airlines
Explore competitive one-way airfare options for ONT - SEA flights. Best suited for flexible or open-ended travel plans.
Flying to Seattle soon? We've surfaced some of the most affordable last-minute flights from Ontario to Seattle, ideal for urgent plans or spontaneous trips.
Looking for the fastest way to Seattle? These direct flight options from ONT to SEA offer both convenience and value—no layovers, just straight to your destination.
Nov 20 - Nov 28, Economy
Ontario → Seattle
7h 15m
8:45 PM - 1:20 AM • nonstop
Ontario → Seattle
4h 5m
10:30 AM - 1:15 PM • nonstop
Southwest Airlines
Nov 20 - Nov 28, Economy
Ontario → Seattle
6h 55m
9:40 AM - 1:55 PM • nonstop
Ontario → Seattle
4h 5m
10:30 AM - 1:15 PM • nonstop
Southwest Airlines
Nov 20 - Nov 28, Economy
Ontario → Seattle
6h 50m
7:00 PM - 11:10 PM • nonstop
Ontario → Seattle
4h 5m
10:30 AM - 1:15 PM • nonstop
Southwest Airlines
Nov 20 - Nov 28, Economy
Ontario → Seattle
7h 15m
3:35 PM - 8:10 PM • nonstop
Ontario → Seattle
4h 5m
10:30 AM - 1:15 PM • nonstop
Southwest Airlines
Nov 20 - Nov 28, Economy
Ontario → Seattle
4h 19m
11:57 AM - 2:56 PM • nonstop
Ontario → Seattle
4h 6m
2:30 PM - 5:16 PM • nonstop
Delta Airlines
FAQs on Ontario to Seattle Flights
What are the airports in Ontario?
ONT
What’s the most popular airline flying from ONT to SEA?
The most popular airline flying from Ontario to Seattle are
Can I fly from ONT to SEA non-stop?
Yes, you can fly ONT to SEA non-stop on
Which airlines fly nonstop between Ontario and Seattle?
The non-stop flights between Ontario and Seattle are .
What’s the earliest departure time from ONT to SEA Airport?
The earliest flight leaves ONT at 5:20 am and lands in SEA - Seattle Tacoma International
What are the airports in Seattle?
SEA
Can I make changes to my Ontario to Seattle flight tickets or cancel them on FareLeaders.com?
No. We are an airfare comparison site. All the tickets are booked by the travel agent offering the flight deal and any changes or cancellations to be made are directly done directly by them or the airlines.
Can I cancel my flight tickets from ONT to SEA?
Read the fare rules of the Ontario to Seattle air tickets booked. Some airlines allow you to cancel the tickets within a stipulated time period with a cancellation fee.
Which airline alliances offer flights from Ontario and Seattle?
operate flights between Ontario and Seattle
How long does a flight from Ontario to Seattle take?
It takes approximately 3 hour to fly non-stop from ONT to SEA, which is 956.13 miles by air.
Which airlines provide the cheapest flights from Ontario (ONT) to Seattle (SEA) ?
In the past couple of days, the cheapest tickets to SEA from ONT were found on WN : USD 140
Do I need a passport to fly between ONT and SEA?
No
What’s the latest departure time from ONT to SEA ?
The last flight leaves ONT at 8:45 pm
Ontario (ONT) to Seattle (SEA): Airport Information
| Origin Airport | Ontario International , Ontario, US |
| Destination Airport | Seattle Tacoma International , Seattle, US |
| Distance | 956 miles |
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