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

Return flights

30 Sep - 25 Oct	Frontier Airlines
27 Sep - 02 Oct	Frontier Airlines
11 Sep - 18 Sep	Frontier Airlines
19 Sep - 22 Sep	Frontier Airlines
18 Sep - 21 Sep	Frontier Airlines
25 Sep - 10 Oct	Frontier Airlines
25 Sep - 01 Oct	Frontier Airlines
24 Sep - 08 Oct	Frontier Airlines
08 Sep - 21 Sep	Frontier Airlines
25 Sep - 11 Oct	Frontier Airlines
30 Sep - 13 Oct	Delta
27 Sep - 03 Oct	Delta

Also check the deals for one-way flights from Chicago to Zurich 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 Zurich in September from 610€

Return flights