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

Return flights

14 Sep - 25 Sep	Delta
30 Sep - 08 Oct	Air France
30 Sep - 07 Oct	Air France
30 Sep - 06 Oct	Air France
07 Sep - 27 Sep	Frontier Airlines
22 Sep - 28 Sep	Frontier Airlines
27 Sep - 04 Oct	Delta
19 Sep - 03 Oct	Delta
20 Sep - 23 Sep	Frontier Airlines
25 Sep - 28 Sep	Frontier Airlines
18 Sep - 21 Sep	Frontier Airlines
19 Sep - 21 Sep	Delta
11 Sep - 18 Sep	Frontier Airlines
19 Sep - 27 Sep	Delta
19 Sep - 22 Sep	KLM
26 Sep - 07 Oct	Frontier Airlines
27 Sep - 02 Oct	Porter Airlines (Canada) Ltd
08 Sep - 04 Oct	Air France
26 Sep - 01 Oct	Frontier Airlines

Also check the deals for one-way flights from Chicago 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 Chicago to Dublin in September from 435€

Return flights