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

Return flights

25 Sep - 30 Sep	TAP
25 Sep - 29 Sep	TAP
29 Sep - 17 Oct	Scandinavian Airlines
16 Sep - 22 Sep	Scandinavian Airlines
14 Sep - 25 Sep	Aer Lingus	direct
01 Sep - 09 Sep	Aer Lingus	direct
09 Sep - 16 Sep	Aer Lingus	direct
03 Sep - 10 Sep	Aer Lingus	direct
09 Sep - 14 Sep	Scandinavian Airlines
23 Sep - 29 Sep	Scandinavian Airlines
09 Sep - 18 Sep	Aer Lingus	direct
29 Sep - 17 Oct	Aer Lingus	direct
30 Sep - 07 Oct	Aer Lingus	direct
17 Sep - 01 Oct	Aer Lingus
17 Sep - 01 Oct	Finnair	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 356€

Return flights