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

One-Way flights

21 Sep	Porter Airlines (Canada) Ltd
29 Sep	Porter Airlines (Canada) Ltd
28 Sep	Porter Airlines (Canada) Ltd
12 Sep	Frontier Airlines
18 Sep	Porter Airlines (Canada) Ltd
02 Sep	Porter Airlines (Canada) Ltd
11 Sep	Porter Airlines (Canada) Ltd
04 Sep	Porter Airlines (Canada) Ltd
26 Sep	Porter Airlines (Canada) Ltd
10 Sep	Porter Airlines (Canada) Ltd

Also check the deals for return 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 one-way flights from Chicago to Dublin in September from 178€

One-Way flights