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

Return flights

28 Sep - 12 Oct	easyJet	direct
14 Sep - 24 Sep	easyJet	direct
23 Sep - 01 Oct	easyJet
07 Sep - 17 Sep	easyJet	direct
14 Sep - 17 Sep	easyJet	direct
28 Sep - 04 Oct	easyJet
24 Sep - 08 Oct	easyJet
28 Sep - 28 Sep	easyJet
03 Sep - 17 Sep	easyJet	direct
24 Sep - 01 Oct	easyJet	direct
10 Sep - 17 Sep	easyJet	direct
30 Sep - 05 Oct	Wizz Air
30 Sep - 07 Oct	Wizz Air
30 Sep - 08 Oct	Wizz Air
16 Sep - 01 Oct	easyJet
29 Sep - 04 Oct	Wizz Air
24 Sep - 30 Sep	Wizz Air
14 Sep - 18 Sep	easyJet
24 Sep - 28 Sep	Wizz Air
13 Sep - 16 Sep	Wizz Air

Also check the deals for one-way flights from London to Keflavik 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 Keflavik in September from 123€

Return flights