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

Return flights

23 Dec - 27 Dec	Icelandair	direct
18 Dec - 25 Dec	Icelandair	direct
18 Dec - 26 Dec	Icelandair	direct
22 Dec - 25 Dec	Sun Country Airlines
17 Dec - 21 Dec	Southwest Airlines
21 Dec - 28 Dec	Sun Country Airlines
21 Dec - 25 Dec	Sun Country Airlines
26 Dec - 28 Dec	Frontier Airlines
20 Dec - 27 Dec	Icelandair	direct
22 Dec - 28 Dec	Icelandair	direct
31 Dec - 05 Jan	Icelandair
31 Dec - 05 Jan	Icelandair	direct
26 Dec - 01 Jan	Spirit Airlines
25 Dec - 01 Jan	Spirit Airlines
27 Dec - 03 Jan	Key Lime Air dba Denver Air Connection
25 Dec - 03 Jan	Spirit Airlines

Also check the deals for one-way flights from Chicago 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 Chicago to Keflavik in December from $723

Return flights