AirHint found the following cheapest return flights from Chicago (MDW) to Prague (PRG) in September 2025 (see full year).

Return flights

25 Sep - 06 Oct	Frontier Airlines
26 Sep - 20 Oct	Frontier Airlines
30 Sep - 21 Oct	Delta
15 Sep - 22 Sep	Delta
17 Sep - 22 Sep	Delta
24 Sep - 30 Sep	Delta
18 Sep - 21 Oct	Delta
25 Sep - 05 Oct	Frontier Airlines
30 Sep - 17 Oct	Delta
08 Sep - 15 Sep	Frontier Airlines
10 Sep - 04 Oct	Frontier Airlines
05 Sep - 13 Sep	Frontier Airlines
11 Sep - 04 Oct	Frontier Airlines

Also check the deals for one-way flights from Chicago to Prague 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 Chicago to Prague in September from $718

Return flights