AirHint found the following cheapest return flights from Washington (DCA) to Seoul (ICN) in September 2025 (see full year).

Return flights

23 Sep - 29 Sep	Alaska Airlines
30 Sep - 05 Oct	Air Canada
29 Sep - 01 Oct	Air Canada
30 Sep - 12 Oct	Air Canada
22 Sep - 17 Oct	Air Canada
14 Sep - 21 Sep	Air Canada
26 Sep - 14 Oct	Air Canada
11 Sep - 03 Oct	Air Canada
12 Sep - 19 Sep	Air Canada
13 Sep - 20 Sep	Air Canada
12 Sep - 30 Sep	Air Canada
13 Sep - 27 Sep	Air Canada
21 Sep - 27 Sep	Hawaiian Airlines
26 Sep - 05 Oct	Hawaiian Airlines
30 Sep - 16 Oct	Delta
10 Sep - 06 Oct	Emirates
13 Sep - 06 Oct	Emirates
22 Sep - 25 Sep	Emirates
23 Sep - 28 Sep	Emirates
26 Sep - 28 Sep	Emirates

Also check the deals for one-way flights from Washington to Seoul in September.

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 Washington to Seoul in September from 905€

Return flights