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

Return flights

27 Dec - 20 Jan	Alaska Airlines
27 Dec - 29 Dec	Korean Air	direct
27 Dec - 20 Jan	Korean Air	direct
28 Dec - 11 Jan	Korean Air	direct
27 Dec - 30 Dec	Korean Air	direct
15 Dec - 23 Dec	Korean Air
28 Dec - 31 Dec	Delta	direct
24 Dec - 30 Dec	Delta
25 Dec - 08 Jan	Delta
26 Dec - 07 Jan	Korean Air
23 Dec - 11 Jan	Korean Air	direct
26 Dec - 07 Jan	Delta	direct
24 Dec - 30 Dec	Korean Air	direct
22 Dec - 11 Jan	Delta
26 Dec - 06 Jan	Air Canada
25 Dec - 08 Jan	Hawaiian Airlines	direct
15 Dec - 23 Dec	Korean Air	direct
17 Dec - 24 Dec	Hawaiian Airlines
16 Dec - 25 Dec	Korean Air
18 Dec - 23 Dec	Hawaiian 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 $846

Return flights