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

Return flights

09 Sep - 16 Sep	Spirit Airlines
10 Sep - 14 Sep	Spirit Airlines
15 Sep - 23 Sep	Spirit Airlines
23 Sep - 07 Oct	Spirit Airlines
07 Sep - 23 Sep	TAP
21 Sep - 26 Sep	TAP
24 Sep - 28 Sep	Spirit Airlines
08 Sep - 06 Oct	Condor
21 Sep - 09 Oct	TAP
19 Sep - 22 Sep	Spirit Airlines
04 Sep - 19 Sep	Spirit Airlines
01 Sep - 18 Sep	Turkish Airlines
19 Sep - 24 Sep	Spirit Airlines
17 Sep - 01 Oct	Spirit Airlines
02 Sep - 04 Oct	Icelandair
05 Sep - 04 Oct	Icelandair
02 Sep - 03 Oct	Air Canada
02 Sep - 03 Oct	United	direct
24 Sep - 01 Oct	Icelandair
30 Sep - 07 Oct	Icelandair

Also check the deals for one-way flights from Chicago to Frankfurt 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 Frankfurt in September from 522€

Return flights