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

Return flights

26 Aug - 30 Sep	Air Canada
25 Aug - 17 Sep	Air Canada
27 Aug - 18 Sep	Air Canada
28 Aug - 25 Sep	Air Canada
27 Aug - 24 Sep	Air Canada
20 Aug - 17 Sep	Air Canada
19 Aug - 16 Sep	Air Canada
26 Aug - 20 Sep	Air Canada
28 Aug - 20 Sep	Air Canada
25 Aug - 19 Sep	Air Canada
22 Aug - 28 Aug	Delta	direct
20 Aug - 27 Aug	Delta
17 Aug - 27 Aug	Delta
17 Aug - 27 Aug	Delta	direct
20 Aug - 27 Aug	Delta	direct
19 Aug - 21 Aug	Delta	direct
18 Aug - 25 Aug	Delta	direct

Also check the deals for one-way flights from Seattle to Seoul in August.

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 August from 681€

Return flights