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

Return flights

03 Dec - 12 Dec	Japan Airlines
04 Dec - 12 Dec	Japan Airlines
01 Dec - 08 Dec	Japan Airlines
01 Dec - 07 Dec	Japan Airlines
17 Dec - 19 Jan	Japan Airlines
10 Dec - 23 Dec	Japan Airlines
06 Dec - 12 Dec	Japan Airlines
15 Dec - 19 Jan	Japan Airlines
16 Dec - 19 Jan	Japan Airlines
13 Dec - 19 Dec	Japan Airlines
24 Dec - 28 Dec	ANA
26 Dec - 09 Jan	ANA
27 Dec - 09 Jan	ANA
21 Dec - 27 Dec	Japan Airlines
21 Dec - 19 Jan	Japan Airlines
22 Dec - 19 Jan	Japan Airlines
01 Dec - 01 Jan	ANA
27 Dec - 31 Dec	ANA
18 Dec - 19 Jan	Japan Airlines
19 Dec - 19 Jan	Japan Airlines

Also check the deals for one-way flights from Seattle to Seoul 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 Seoul in December from $885

Return flights