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

Return flights

23 Sep - 31 Oct	Korean Air
24 Sep - 07 Oct	Korean Air
24 Sep - 08 Oct	Korean Air
22 Sep - 08 Oct	Korean Air
24 Sep - 29 Oct	Korean Air
25 Sep - 30 Sep	American Airlines
24 Sep - 06 Oct	Korean Air
26 Sep - 05 Oct	Korean Air
28 Sep - 08 Oct	Korean Air
28 Sep - 04 Oct	Korean Air
19 Sep - 21 Sep	Korean Air
20 Sep - 26 Sep	Korean Air
19 Sep - 26 Sep	Korean Air
26 Sep - 08 Oct	Korean Air
20 Sep - 27 Sep	Hawaiian Airlines
25 Sep - 28 Sep	Hawaiian Airlines
26 Sep - 28 Sep	Korean Air
19 Sep - 27 Sep	Korean Air
22 Sep - 29 Sep	Korean Air
22 Sep - 26 Sep	Korean Air

Also check the deals for one-way flights from San Jose 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 San Jose to Seoul in September from $833

Return flights