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

Return flights

04 Dec - 11 Dec	Spirit Airlines
02 Dec - 07 Dec	Spirit Airlines
23 Dec - 17 Jan	jetBlue
19 Dec - 10 Jan	jetBlue
21 Dec - 10 Jan	jetBlue
26 Dec - 17 Jan	jetBlue
26 Dec - 28 Dec	Frontier Airlines
27 Dec - 31 Dec	Frontier Airlines
20 Dec - 10 Jan	Frontier Airlines
20 Dec - 28 Dec	Frontier Airlines
27 Dec - 30 Dec	Sun Country Airlines
23 Dec - 02 Jan	Frontier Airlines
27 Dec - 01 Jan	Sun Country Airlines
26 Dec - 31 Dec	Frontier Airlines
28 Dec - 04 Jan	Frontier Airlines

Also check the deals for one-way flights from Atlanta 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 Atlanta to Keflavik in December from $490

Return flights