AirHint found the following cheapest return flights from Seoul (GMP) to Hanoi (HAN) in September 2025 (see full year).

Return flights

22 Sep - 25 Sep	T'way Air
24 Sep - 28 Sep	Jin Air
22 Sep - 01 Oct	Air Busan
20 Sep - 24 Sep	Air Busan
05 Sep - 12 Sep	Air Busan
08 Sep - 17 Sep	Air China
04 Sep - 09 Sep	Air China
17 Sep - 22 Sep	Air China
23 Sep - 25 Sep	Air China
18 Sep - 23 Sep	Air China
23 Sep - 26 Sep	Air China
17 Sep - 31 Oct	Air China
17 Sep - 30 Oct	Air China
18 Sep - 31 Oct	Air China
29 Sep - 13 Oct	China Eastern
24 Sep - 02 Oct	Air China
23 Sep - 05 Oct	Air China
08 Sep - 14 Oct	Air China
29 Sep - 06 Oct	Korean Air
28 Sep - 03 Oct	Air China

Also check the deals for one-way flights from Seoul to Hanoi 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 Seoul to Hanoi in September from 176€

Return flights