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

Return flights

22 Sep - 13 Oct	TAP
01 Sep - 17 Oct	TAP
30 Sep - 18 Oct	Ryanair
23 Sep - 11 Oct	TAP
06 Sep - 22 Sep	TAP
08 Sep - 24 Sep	TAP
01 Sep - 09 Sep	Air Europa
02 Sep - 17 Sep	SWISS
03 Sep - 23 Sep	TAP
01 Sep - 17 Sep	TAP
03 Sep - 17 Sep	TAP
15 Sep - 25 Sep	SWISS
03 Sep - 07 Sep	Azul Airlines
07 Sep - 14 Sep	TAP

Also check the deals for one-way flights from Porto to Buenos Aires 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 Buenos Aires in September from 900€

Return flights