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

Return flights

30 Sep - 08 Oct	Icelandair
10 Sep - 18 Sep	Air Canada
09 Sep - 17 Sep	Air Canada
27 Sep - 05 Oct	Icelandair
29 Sep - 07 Oct	Icelandair
03 Sep - 11 Sep	Air Canada
08 Sep - 16 Sep	Air Canada
17 Sep - 25 Sep	Icelandair
01 Sep - 09 Sep	SWISS
02 Sep - 10 Sep	Lufthansa
14 Sep - 22 Sep	Air Canada
28 Sep - 10 Oct	Air Canada
29 Sep - 10 Oct	Air Canada
15 Sep - 23 Sep	Air Canada
16 Sep - 24 Sep	Air Canada
17 Sep - 03 Oct	Air Canada
30 Sep - 15 Oct	Icelandair
27 Sep - 10 Oct	Air Canada
23 Sep - 01 Oct	Air France
29 Sep - 11 Oct	Air Canada

Also check the deals for one-way flights from Denver to Dublin 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 Dublin in September from 303€

Return flights