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

Return flights

09 Sep - 22 Sep	Air Canada
21 Sep - 29 Sep	Air Canada
09 Sep - 17 Sep	Air Canada
08 Sep - 17 Sep	Air Canada
02 Sep - 16 Sep	Air Canada
18 Sep - 25 Sep	Air Canada
29 Sep - 20 Oct	Air Canada
01 Sep - 19 Sep	Air Canada
24 Sep - 28 Sep	Air Canada
01 Sep - 31 Oct	Air Canada
05 Sep - 21 Sep	WestJet
15 Sep - 15 Oct	Hawaiian Airlines
09 Sep - 25 Sep	Hawaiian Airlines
28 Sep - 02 Oct	Air Canada
26 Sep - 01 Oct	Air Canada
15 Sep - 15 Oct	Delta	direct
29 Sep - 20 Oct	Delta	direct
26 Sep - 01 Oct	Delta	direct
28 Sep - 02 Oct	Delta	direct
01 Sep - 31 Oct	Delta	direct

Also check the deals for one-way flights from Seattle 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 Seattle to Seoul in September from 707€

Return flights