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

Return flights

08 Sep - 15 Sep	Spirit Airlines
09 Sep - 16 Sep	Scandinavian Airlines
06 Sep - 10 Oct	Turkish Airlines
24 Sep - 01 Oct	Icelandair
17 Sep - 24 Sep	United
30 Sep - 07 Oct	United
13 Sep - 24 Sep	United
04 Sep - 14 Sep	Scandinavian Airlines
01 Sep - 08 Sep	United	direct
15 Sep - 22 Sep	United
19 Sep - 26 Sep	United
11 Sep - 21 Sep	Air Canada
27 Sep - 04 Oct	United
09 Sep - 16 Sep	Brussels Airlines	direct
06 Sep - 10 Oct	Brussels Airlines	direct

Also check the deals for one-way flights from Chicago to Brussels 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 Brussels in September from 468€

Return flights