Cheap Flights from Seattle to Ontario

View €85 flight on Tue, 16 Sep 2025Opens in a new window

Popular airlines from Seattle to Ontario

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Cheap flights from Seattle to Ontario (SEA-QLA)

Prices were available within the past 7 days and start at €85 for one-way flights and €203 for round trip, for the period specified. Prices and availability are subject to change. Additional terms apply.

Delta
Thu, 14 Aug - Mon, 18 Aug
SEA
Seattle
ONT
Ontario
€203 Return, found 4 days ago
€203
Return
found 4 days ago
Select Delta flight, departing Thu, 14 Aug from Seattle to Ontario, returning Mon, 18 Aug, priced at €203 found 4 days ago
Delta
Thu, 14 Aug - Mon, 18 Aug
SEA
Seattle
ONT
Ontario
€227 Return, found 4 days ago
€227
Return
found 4 days ago
Select Delta flight, departing Thu, 14 Aug from Seattle to Ontario, returning Mon, 18 Aug, priced at €227 found 4 days ago
Delta
Thu, 14 Aug - Mon, 18 Aug
SEA
Seattle
ONT
Ontario
€241 Return, found 4 days ago
€241
Return
found 4 days ago
Select Delta flight, departing Thu, 14 Aug from Seattle to Ontario, returning Mon, 18 Aug, priced at €241 found 4 days ago
American Airlines
Thu, 14 Aug - Mon, 18 Aug
SEA
Seattle
ONT
Ontario
€245 Return, found 4 days ago
€245
Return
found 4 days ago
Select American Airlines flight, departing Thu, 14 Aug from Seattle to Ontario, returning Mon, 18 Aug, priced at €245 found 4 days ago
United
Thu, 14 Aug - Mon, 18 Aug
SEA
Seattle
ONT
Ontario
€258 Return, found 4 days ago
€258
Return
found 4 days ago
Select United flight, departing Thu, 14 Aug from Seattle to Ontario, returning Mon, 18 Aug, priced at €258 found 4 days ago
Alaska Airlines
Thu, 14 Aug - Mon, 18 Aug
PAE
Seattle
ONT
Ontario
€719 Return, found 4 days ago
€719
Return
found 4 days ago
Select Alaska Airlines flight, departing Thu, 14 Aug from Seattle to Ontario, returning Mon, 18 Aug, priced at €719 found 4 days ago

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

October is typically the cheapest month to fly

From €56 - €161 per traveller.

Graph displaying average flight prices per month

*Available to Expedia members.