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

Return flights

03 Sep - 24 Sep	Alaska Airlines
25 Sep - 20 Oct	Air Canada
08 Sep - 15 Sep	Air Canada
04 Sep - 11 Sep	Air Canada
30 Sep - 14 Oct	Air Canada
12 Sep - 24 Sep	Hawaiian Airlines
24 Sep - 28 Sep	Air Canada
08 Sep - 19 Sep	Air Canada
05 Sep - 26 Sep	Air Canada
24 Sep - 01 Oct	Hawaiian Airlines
26 Sep - 05 Oct	WestJet
25 Sep - 02 Oct	United
28 Sep - 03 Oct	American Airlines
22 Sep - 29 Sep	Emirates
25 Sep - 15 Oct	Emirates
12 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 933€

Return flights