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

Return flights

07 Sep - 14 Sep	Frontier Airlines
08 Sep - 15 Sep	WestJet
13 Sep - 20 Sep	Frontier Airlines
16 Sep - 23 Sep	Air China
06 Sep - 13 Sep	Alaska Airlines
09 Sep - 24 Sep	Alaska Airlines
28 Sep - 05 Oct	Frontier Airlines
15 Sep - 14 Oct	Turkish Airlines
02 Sep - 10 Sep	Turkish Airlines
16 Sep - 21 Oct	Turkish Airlines
30 Sep - 15 Oct	Air Canada
30 Sep - 23 Oct	Air Canada
22 Sep - 21 Oct	Air Canada
16 Sep - 20 Oct	Air Canada
26 Sep - 29 Sep	Frontier Airlines
05 Sep - 08 Sep	Air Canada
26 Sep - 13 Oct	Air Canada
18 Sep - 02 Oct	Alaska Airlines
01 Sep - 05 Sep	Air Canada
19 Sep - 02 Oct	Frontier Airlines

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.

Book a cheap hotel in Seoul

Cheap car rent in Seoul

Cheapest return flights from Washington to Seoul in September from 795€

Return flights