Cheap flights from Seattle to Ontario

View AU$136 flight on Wed, 27 Aug. 2025Opens in a new window

Popular airlines from Seattle to Ontario

  • Plan, book, fly with confidence

  • trending down icon

    Be in the know

    Get alerts if flight prices drop or rise*
  • bex rewards loyalty icon

    Book smarter

    Save up to 35% on select hotels after you book a flight*
  • payments icon

    Earn twice

    Earn your airline miles on top of our rewards
    Sign in

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

Prices were available within the past 7 days for one-way flights and round trip tickets for the period specified. Prices and availability are subject to change. Additional terms apply.

Hawaiian Airlines
Sat, 16 Aug. - Tue, 19 Aug.
SEA
Seattle
ONT
Ontario
AU$210 Return, found 12 hours ago
AU$210
Return
found 12 hours ago
Select Hawaiian Airlines flight, departing Sat, 16 Aug. from Seattle to Ontario, returning Tue, 19 Aug., priced at AU$210 found 12 hours ago
Delta
Wed, 20 Aug. - Sat, 30 Aug.
SEA
Seattle
ONT
Ontario
AU$211 Return, found 6 days ago
AU$211
Return
found 6 days ago
Select Delta flight, departing Wed, 20 Aug. from Seattle to Ontario, returning Sat, 30 Aug., priced at AU$211 found 6 days ago
Hawaiian Airlines
Wed, 20 Aug. - Tue, 2 Sep.
SEA
Seattle
ONT
Ontario
AU$211 Return, found 6 days ago
AU$211
Return
found 6 days ago
Select Hawaiian Airlines flight, departing Wed, 20 Aug. from Seattle to Ontario, returning Tue, 2 Sep., priced at AU$211 found 6 days ago
Hawaiian Airlines
Thu, 14 Aug. - Tue, 19 Aug.
SEA
Seattle
ONT
Ontario
AU$256 Return, found 12 hours ago
AU$256
Return
found 12 hours ago
Select Hawaiian Airlines flight, departing Thu, 14 Aug. from Seattle to Ontario, returning Tue, 19 Aug., priced at AU$256 found 12 hours ago
Alaska Airlines
Thu, 21 Aug. - Sun, 31 Aug.
SEA
Seattle
ONT
Ontario
AU$287 Return, found 6 days ago
AU$287
Return
found 6 days ago
Select Alaska Airlines flight, departing Thu, 21 Aug. from Seattle to Ontario, returning Sun, 31 Aug., priced at AU$287 found 6 days ago
United
Wed, 13 Aug. - Sun, 17 Aug.
SEA
Seattle
ONT
Ontario
AU$356 Return, found 6 days ago
AU$356
Return
found 6 days ago
Select United flight, departing Wed, 13 Aug. from Seattle to Ontario, returning Sun, 17 Aug., priced at AU$356 found 6 days ago

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

October is typically the cheapest month to fly

From AU$100 - AU$286 per traveller.

Graph displaying average flight prices per month

*Available to Expedia members.