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

Return flights

03 Sep - 17 Sep	Air Canada
09 Sep - 19 Sep	SWISS
02 Sep - 15 Sep	SWISS
02 Sep - 10 Sep	Icelandair
09 Sep - 30 Sep	Lufthansa
02 Sep - 30 Sep	Lufthansa
08 Sep - 15 Sep	Lufthansa
14 Sep - 27 Sep	Icelandair
06 Sep - 13 Sep	Icelandair
22 Sep - 27 Sep	Icelandair
11 Sep - 23 Oct	Air Canada
11 Sep - 05 Oct	Air France
11 Sep - 23 Oct	Turkish Airlines	direct
19 Sep - 17 Oct	Air France
19 Sep - 17 Oct	Turkish Airlines	direct
11 Sep - 05 Oct	Turkish Airlines	direct
26 Sep - 11 Oct	Turkish Airlines	direct

Also check the deals for one-way flights from Boston to Istanbul 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 Istanbul in September from $541

Return flights