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

Return flights

25 Sep - 16 Oct	China Southern
25 Sep - 26 Oct	China Southern
22 Sep - 27 Oct	China Southern
22 Sep - 16 Oct	China Southern
16 Sep - 16 Oct	China Southern
24 Sep - 26 Oct	China Southern
22 Sep - 24 Oct	China Southern
11 Sep - 21 Oct	China Southern
12 Sep - 18 Oct	China Southern
19 Sep - 13 Oct	China Southern
10 Sep - 15 Sep	Lufthansa
11 Sep - 15 Sep	Lufthansa
04 Sep - 15 Sep	Lufthansa
02 Sep - 15 Sep	SWISS
01 Sep - 15 Sep	SWISS
13 Sep - 16 Sep	China Southern
08 Sep - 16 Sep	Lufthansa
06 Sep - 16 Sep	China Southern
07 Sep - 15 Sep	SWISS
04 Sep - 16 Sep	Lufthansa

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.

Book a cheap hotel in Seoul

Cheap car rent in Seoul

Cheapest return flights from London to Seoul in September from 451€

Return flights