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

Return flights

09 Sep - 16 Sep	Icelandair
05 Sep - 08 Sep	Icelandair
30 Sep - 07 Oct	Icelandair
24 Sep - 01 Oct	Icelandair
14 Sep - 23 Sep	Icelandair
03 Sep - 10 Sep	Icelandair
12 Sep - 19 Sep	Icelandair
18 Sep - 25 Sep	Icelandair
03 Sep - 06 Sep	Frontier Airlines
27 Sep - 04 Oct	Icelandair
06 Sep - 13 Sep	Icelandair
21 Sep - 28 Sep	United
29 Sep - 04 Oct	Icelandair
05 Sep - 08 Sep	SWISS	direct

Also check the deals for one-way flights from Denver 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 Denver to Zurich in September from 471€

Return flights