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

Return flights

04 Sep - 25 Sep	Avianca
10 Sep - 23 Sep	Avianca
01 Sep - 24 Sep	Avianca
10 Sep - 22 Sep	Avianca
07 Sep - 22 Sep	Avianca
04 Sep - 22 Oct	Avianca
09 Sep - 23 Sep	Avianca
08 Sep - 22 Sep	Avianca
15 Sep - 22 Sep	Avianca
03 Sep - 30 Sep	LATAM Airlines Group
09 Sep - 30 Sep	LATAM Airlines Group
17 Sep - 08 Oct	LATAM Airlines Group
17 Sep - 01 Oct	LATAM Airlines Group
27 Sep - 04 Oct	Avianca
16 Sep - 04 Oct	LATAM Airlines Group
29 Sep - 09 Oct	Avianca
19 Sep - 08 Oct	LATAM Airlines Group
18 Sep - 03 Oct	Avianca
19 Sep - 11 Oct	LATAM Airlines Group
01 Sep - 01 Oct	Air Canada

Also check the deals for one-way flights from London 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 London to Buenos Aires in September from $1058

Return flights