AirHint found the following cheapest return flights from Atlanta (ATL) to Lisbon (LIS) in September 2025 (see full year).

Return flights

23 Sep - 30 Sep	Spirit Airlines
30 Sep - 08 Oct	Spirit Airlines
22 Sep - 29 Sep	Frontier Airlines
28 Sep - 05 Oct	Spirit Airlines
09 Sep - 16 Sep	Frontier Airlines
23 Sep - 14 Oct	jetBlue
03 Sep - 10 Sep	Frontier Airlines
12 Sep - 16 Sep	Frontier Airlines
10 Sep - 25 Sep	jetBlue
11 Sep - 19 Sep	Frontier Airlines
12 Sep - 19 Sep	Frontier Airlines
26 Sep - 05 Oct	jetBlue
19 Sep - 26 Sep	Frontier Airlines
01 Sep - 08 Sep	Frontier Airlines

Also check the deals for one-way flights from Atlanta to Lisbon 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 Atlanta to Lisbon in September from $603

Return flights