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

Return flights

25 Sep - 06 Oct	Cathay Pacific
04 Sep - 11 Sep	United
08 Sep - 17 Sep	United
23 Sep - 22 Oct	Cathay Pacific
08 Sep - 24 Sep	ANA
08 Sep - 15 Sep	ANA
15 Sep - 25 Sep	ANA
09 Sep - 16 Sep	ANA
01 Sep - 07 Sep	Cathay Pacific
10 Sep - 17 Sep	ANA
09 Sep - 14 Sep	Cathay Pacific
02 Sep - 07 Sep	ANA
26 Sep - 31 Oct	Cathay Pacific
29 Sep - 01 Oct	ANA
22 Sep - 06 Oct	United
26 Sep - 04 Oct	Delta
27 Sep - 03 Oct	Delta

Also check the deals for one-way flights from Chicago to Bangkok 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 Bangkok in September from 593€

Return flights