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

Return flights

25 Sep - 29 Sep	KLM
26 Sep - 28 Sep	Delta
26 Sep - 29 Sep	KLM
25 Sep - 01 Oct	KLM
30 Sep - 13 Oct	KLM
30 Sep - 11 Oct	KLM
27 Sep - 03 Oct	Delta
30 Sep - 09 Oct	KLM
25 Sep - 02 Oct	KLM
26 Sep - 02 Oct	Delta
25 Sep - 01 Oct	Iberia	direct
26 Sep - 10 Oct	KLM
25 Sep - 02 Oct	Finnair	direct
25 Sep - 29 Sep	Iberia	direct
22 Sep - 30 Sep	jetBlue	direct
21 Sep - 28 Sep	jetBlue	direct
23 Sep - 30 Sep	jetBlue	direct
20 Sep - 22 Sep	ITA Airways
24 Sep - 28 Sep	TAP
25 Sep - 27 Sep	Vueling Airlines

Also check the deals for one-way flights from Madrid 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 Madrid to Boston in September from $481

Return flights