AirHint found the following cheapest return flights from Keflavik (KEF) to London (LTN) in September 2025 (see full year).

Return flights

17 Sep - 24 Sep	easyJet	direct
10 Sep - 14 Sep	easyJet	direct
10 Sep - 24 Sep	easyJet	direct
21 Sep - 28 Sep	easyJet	direct
29 Sep - 30 Sep	easyJet
03 Sep - 10 Sep	easyJet	direct
20 Sep - 27 Sep	Wizz Air
25 Sep - 29 Sep	Wizz Air
15 Sep - 18 Sep	easyJet
04 Sep - 11 Sep	Fly Play
04 Sep - 03 Oct	Wizz Air

Also check the deals for one-way flights from Keflavik 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 Keflavik to London in September from 136€

Return flights