AirHint found the following cheapest return flights from Chicago (MDW) to Sao Paulo (GRU) in October 2025 (see full year).

Return flights

20 Oct - 27 Oct	Frontier Airlines
03 Oct - 31 Oct	Frontier Airlines
07 Oct - 14 Oct	Frontier Airlines
26 Oct - 03 Nov	Frontier Airlines
27 Oct - 03 Nov	Delta
21 Oct - 28 Oct	Delta
10 Oct - 17 Oct	LATAM Airlines Group
02 Oct - 09 Oct	Delta
02 Oct - 05 Oct	Delta
15 Oct - 22 Oct	LATAM Airlines Group

Also check the deals for one-way flights from Chicago to Sao Paulo in October.

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 Sao Paulo in October from 505€

Return flights