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

Return flights

02 Dec - 08 Dec	easyJet
04 Dec - 08 Dec	easyJet
03 Dec - 08 Dec	easyJet
02 Dec - 06 Dec	easyJet
03 Dec - 07 Dec	easyJet
01 Dec - 08 Dec	easyJet
01 Dec - 06 Dec	easyJet
07 Dec - 12 Dec	Wizz Air
08 Dec - 16 Dec	easyJet
07 Dec - 15 Dec	Wizz Air
31 Dec - 04 Jan	Wizz Air
30 Dec - 02 Jan	easyJet
28 Dec - 02 Jan	Wizz Air
26 Dec - 02 Jan	Wizz Air Malta
26 Dec - 04 Jan	Icelandair
27 Dec - 04 Jan	easyJet

Also check the deals for one-way flights from Keflavik to Istanbul 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 Keflavik to Istanbul in December from $199

Return flights