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

Return flights

11 Sep - 16 Oct	Avianca
08 Sep - 07 Oct	Avianca
18 Sep - 14 Oct	Avianca
09 Sep - 16 Oct	Avianca
18 Sep - 05 Oct	Avianca
15 Sep - 20 Sep	Avianca
17 Sep - 21 Oct	Avianca
18 Sep - 17 Oct	Avianca
28 Sep - 12 Oct	Avianca
29 Sep - 12 Oct	Avianca
17 Sep - 15 Oct	Avianca
11 Sep - 30 Sep	Avianca
05 Sep - 20 Sep	TAP
18 Sep - 30 Sep	Avianca
08 Sep - 27 Sep	Avianca
09 Sep - 28 Sep	Avianca
08 Sep - 29 Sep	Avianca
08 Sep - 30 Sep	Avianca
11 Sep - 25 Sep	Avianca
17 Sep - 30 Sep	Avianca

Also check the deals for one-way flights from Madrid 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 Madrid to Buenos Aires in September from $913

Return flights