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

Return flights

09 Sep - 17 Sep	Cathay Pacific
03 Sep - 09 Sep	Cathay Pacific
08 Sep - 24 Sep	Cathay Pacific
10 Sep - 17 Sep	Cathay Pacific
03 Sep - 10 Sep	Cathay Pacific
06 Sep - 16 Sep	Cathay Pacific
13 Sep - 28 Sep	Cathay Pacific
04 Sep - 18 Sep	Cathay Pacific
06 Sep - 25 Sep	WestJet
21 Sep - 27 Sep	Cathay Pacific
03 Sep - 29 Oct	Spirit Airlines
15 Sep - 06 Oct	Turkish Airlines
25 Sep - 02 Oct	American Airlines
03 Sep - 29 Oct	Delta	direct
15 Sep - 06 Oct	Delta	direct

Also check the deals for one-way flights from Chicago 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 Chicago to Seoul in September from $752

Return flights