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

Return flights

06 Sep - 26 Sep	TAP
01 Sep - 26 Sep	TAP
21 Sep - 28 Sep	TAP
13 Sep - 26 Sep	TAP
01 Sep - 08 Sep	TAP
08 Sep - 30 Sep	TAP
22 Sep - 30 Sep	TAP
20 Sep - 29 Sep	TAP
06 Sep - 19 Sep	TAP
22 Sep - 29 Sep	TAP
20 Sep - 03 Oct	TAP
22 Sep - 01 Oct	TAP
24 Sep - 02 Oct	KLM
28 Sep - 05 Oct	Iberia	direct
29 Sep - 06 Oct	Iberia	direct
20 Sep - 03 Oct	Iberia	direct
26 Sep - 01 Oct	TAP
25 Sep - 02 Oct	British Airways
20 Sep - 02 Oct	British Airways
26 Sep - 03 Oct	Finnair

Also check the deals for one-way flights from Chicago to Madrid 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 Madrid in September from 254€

Return flights