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

Return flights

26 Oct - 04 Nov	Icelandair	direct
19 Oct - 23 Oct	Frontier Airlines
17 Oct - 21 Oct	Frontier Airlines
15 Oct - 21 Oct	Spirit Airlines
13 Oct - 15 Oct	Frontier Airlines
21 Oct - 01 Nov	Icelandair	direct
21 Oct - 27 Oct	Icelandair	direct
19 Oct - 23 Oct	Icelandair	direct
01 Oct - 09 Oct	Spirit Airlines
09 Oct - 14 Oct	Austrian Airlines
01 Oct - 05 Oct	Spirit Airlines
17 Oct - 21 Oct	Icelandair	direct

Also check the deals for one-way flights from Chicago to Keflavik in October.

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 October from 341€

Return flights