AirHint found the following cheapest return flights from Seattle (SEA) to Barcelona (BCN) in December 2025 (see full year).

Return flights

09 Dec - 16 Dec	Air Canada
03 Dec - 10 Dec	Air Canada
10 Dec - 17 Dec	Air Canada
08 Dec - 15 Dec	Air Canada
01 Dec - 08 Dec	Air Canada
02 Dec - 09 Dec	Lufthansa
04 Dec - 11 Dec	Air Canada
05 Dec - 12 Dec	Icelandair
07 Dec - 14 Dec	Air Canada
06 Dec - 13 Dec	Air Canada
31 Dec - 07 Jan	Scandinavian Airlines
30 Dec - 06 Jan	Alaska Airlines
29 Dec - 05 Jan	Air Canada
25 Dec - 01 Jan	Turkish Airlines
28 Dec - 04 Jan	Alaska Airlines
27 Dec - 03 Jan	Alaska Airlines
26 Dec - 02 Jan	Turkish Airlines
20 Dec - 05 Jan	Scandinavian Airlines

Also check the deals for one-way flights from Seattle to Barcelona in December.

The deals are updated regularly. The prices may go up as tickets are purchased by other travellers. Only the cheapest flights are offered. Select a price to book and secure these cheap prices.

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Cheapest return flights from Seattle to Barcelona in December from $419

Return flights