AirHint found the following cheapest return flights from Keflavik (KEF) to Boston (BOS) in September 2025 (see full year).

Return flights

11 Sep - 15 Sep	Fly Play	direct
23 Sep - 03 Oct	Icelandair	direct
16 Sep - 24 Sep	Icelandair	direct
02 Sep - 06 Sep	Icelandair	direct

Also check the deals for one-way flights from Keflavik to Boston in September.

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 Boston in September from $275

Return flights