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

Return flights

29 Sep - 20 Oct	China Southern
30 Sep - 21 Oct	China Southern
29 Sep - 06 Oct	China Eastern
25 Sep - 28 Sep	Japan Airlines
25 Sep - 02 Oct	ANA
26 Sep - 30 Sep	China Eastern
25 Sep - 03 Oct	China Eastern
29 Sep - 14 Oct	Air China
25 Sep - 30 Sep	Japan Airlines
30 Sep - 07 Oct	China Eastern
29 Sep - 12 Oct	Air China
29 Sep - 07 Oct	China Southern
22 Sep - 27 Oct	ANA
25 Sep - 27 Sep	Air China
23 Sep - 28 Sep	Air China
26 Sep - 27 Sep	Air China
26 Sep - 28 Sep	Air China
27 Sep - 28 Sep	Air China
26 Sep - 29 Sep	ANA

Also check the deals for one-way flights from Seoul to London 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 London in September from 738€

Return flights