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

Return flights

10 Sep - 17 Sep	Porter Airlines (Canada) Ltd
15 Sep - 18 Sep	Air Canada
01 Sep - 08 Sep	Air Canada
06 Sep - 13 Sep	Air Canada
19 Sep - 13 Oct	United
16 Sep - 12 Oct	United
18 Sep - 12 Oct	United
18 Sep - 11 Oct	United
12 Sep - 19 Sep	United
13 Sep - 20 Sep	United
16 Sep - 23 Sep	United
17 Sep - 24 Sep	United
19 Sep - 26 Sep	United
21 Sep - 28 Sep	United
24 Sep - 01 Oct	United
27 Sep - 04 Oct	United
26 Sep - 03 Oct	United
29 Sep - 06 Oct	United
25 Sep - 02 Oct	United
19 Sep - 13 Oct	Delta	direct

Also check the deals for one-way flights from Boston 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 Boston to Seoul in September from 789€

Return flights