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

Return flights

30 Sep - 08 Oct	Air Canada
30 Sep - 07 Oct	Air Canada
29 Sep - 17 Oct	Air Canada
29 Sep - 14 Oct	Aer Lingus	direct
29 Sep - 17 Oct	United	direct
24 Sep - 01 Oct	Air Canada
30 Sep - 06 Oct	Aer Lingus	direct
27 Sep - 18 Oct	Air Canada
23 Sep - 18 Oct	SWISS
27 Sep - 06 Oct	Aer Lingus	direct
25 Sep - 28 Sep	SWISS
19 Sep - 23 Sep	jetBlue
19 Sep - 24 Sep	jetBlue
22 Sep - 26 Sep	Spirit Airlines
25 Sep - 30 Sep	Frontier Airlines
26 Sep - 28 Sep	Air Canada
25 Sep - 29 Sep	Frontier Airlines
22 Sep - 29 Sep	Frontier Airlines
23 Sep - 30 Sep	SWISS
19 Sep - 23 Sep	Aer Lingus	direct

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 $530

Return flights