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

Return flights

10 Dec - 15 Dec	KLM
11 Dec - 15 Dec	KLM
15 Dec - 22 Dec	KLM
08 Dec - 15 Dec	KLM
04 Dec - 08 Dec	KLM
04 Dec - 07 Dec	KLM
10 Dec - 17 Dec	KLM
03 Dec - 07 Dec	KLM
08 Dec - 12 Dec	KLM
01 Dec - 05 Dec	KLM
31 Dec - 07 Jan	KLM
31 Dec - 08 Jan	KLM
24 Dec - 08 Jan	KLM
24 Dec - 01 Jan	KLM
18 Dec - 01 Jan	KLM
22 Dec - 08 Jan	KLM
31 Dec - 01 Jan	KLM
24 Dec - 06 Jan	KLM
29 Dec - 05 Jan	KLM
30 Dec - 06 Jan	Lufthansa

Also check the deals for one-way flights from London to Keflavik in December.

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 December from $270

Return flights