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

Return flights

10 Sep - 22 Sep	Air Canada
11 Sep - 16 Sep	Air Canada
17 Sep - 08 Oct	Air Canada
04 Sep - 17 Sep	Air Canada
10 Sep - 15 Sep	Air Canada
06 Sep - 20 Sep	Air Canada
21 Sep - 28 Sep	Air Canada
07 Sep - 17 Sep	Air Canada
24 Sep - 30 Sep	Air Canada
06 Sep - 17 Oct	Air Canada
03 Sep - 05 Oct	Air Canada
03 Sep - 10 Sep	Air Canada
10 Sep - 14 Sep	Frontier Airlines
30 Sep - 16 Oct	Air Canada
26 Sep - 05 Oct	Frontier Airlines
26 Sep - 17 Oct	Frontier Airlines
27 Sep - 02 Oct	Air Canada
09 Sep - 02 Oct	Air Canada
30 Sep - 14 Oct	Alaska Airlines
29 Sep - 16 Oct	Air Canada

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 $928

Return flights