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

Return flights

30 Sep - 14 Oct	Pegasus Airlines
24 Sep - 12 Oct	Ryanair
01 Sep - 15 Sep	Ryanair
24 Sep - 30 Oct	Pegasus Airlines
02 Sep - 16 Sep	Ryanair
03 Sep - 11 Sep	Ryanair
01 Sep - 14 Sep	Ryanair
09 Sep - 16 Sep	Ryanair
09 Sep - 15 Sep	Ryanair
01 Sep - 12 Sep	Ryanair
06 Sep - 16 Sep	Ryanair
22 Sep - 20 Oct	Ryanair
16 Sep - 24 Sep	Ryanair
24 Sep - 13 Oct	Pegasus Airlines
10 Sep - 17 Sep	Ryanair
01 Sep - 25 Oct	Ryanair
24 Sep - 21 Oct	Ryanair
19 Sep - 13 Oct	Ryanair
26 Sep - 17 Oct	Ryanair
24 Sep - 09 Oct	Ryanair

Also check the deals for one-way flights from London 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 London to Seoul in September from 501€

Return flights