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

Return flights

17 Sep - 24 Sep	Ryanair
17 Sep - 22 Sep	Ryanair
17 Sep - 23 Sep	Ryanair
23 Sep - 06 Oct	easyJet
25 Sep - 01 Oct	easyJet
17 Sep - 21 Sep	Ryanair
16 Sep - 20 Sep	Ryanair
16 Sep - 26 Sep	Ryanair
12 Sep - 30 Sep	easyJet
25 Sep - 30 Sep	easyJet
18 Sep - 22 Sep	easyJet
16 Sep - 22 Sep	Transavia France
27 Sep - 02 Oct	TAP
26 Sep - 08 Oct	Ryanair
27 Sep - 04 Oct	Transavia France
20 Sep - 03 Oct	easyJet
29 Sep - 05 Oct	Wizz Air Malta
08 Sep - 30 Oct	easyJet
24 Sep - 14 Oct	Vueling Airlines
24 Sep - 01 Oct	Vueling Airlines

Also check the deals for one-way flights from Porto 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 Porto to Istanbul in September from $209

Return flights