AirHint found the following cheapest return flights from Chicago (ORD) to Sydney (SYD) in October 2025 (see full year).

Return flights

22 Oct - 24 Oct	Alaska Airlines
22 Oct - 31 Oct	Frontier Airlines
27 Oct - 03 Nov	Hawaiian Airlines
29 Oct - 26 Nov	Hawaiian Airlines
18 Oct - 26 Oct	Hawaiian Airlines
14 Oct - 29 Oct	Frontier Airlines
23 Oct - 07 Nov	Hawaiian Airlines
06 Oct - 13 Oct	Hawaiian Airlines
07 Oct - 25 Nov	Fiji Airways
24 Oct - 26 Oct	Turkish Airlines

Also check the deals for one-way flights from Chicago to Sydney 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 Sydney in October from $961

Return flights