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

Return flights

22 Sep - 29 Sep	Air Canada
21 Sep - 01 Oct	Iberia For Level
29 Sep - 07 Oct	Iberia For Level
28 Sep - 15 Oct	Iberia For Level
29 Sep - 06 Oct	Iberia For Level
22 Sep - 06 Oct	Iberia For Level
24 Sep - 01 Oct	SWISS
21 Sep - 30 Sep	Air Canada
01 Sep - 09 Sep	Air Canada
08 Sep - 15 Sep	Iberia For Level
10 Sep - 17 Sep	Iberia For Level
14 Sep - 22 Sep	Iberia For Level
24 Sep - 29 Sep	Air Canada
15 Sep - 23 Sep	Air Canada
21 Sep - 02 Oct	Iberia
16 Sep - 24 Sep	Air Canada
03 Sep - 08 Sep	Iberia
07 Sep - 05 Oct	Iberia For Level
27 Sep - 05 Oct	Icelandair
07 Sep - 19 Oct	Iberia

Also check the deals for one-way flights from Boston to Lisbon 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 Boston to Lisbon in September from $376

Return flights