AirHint found the following cheapest return flights from Ontario (ONT) to Kathmandu (KTM) in September 2025 (see full year).

Return flights

14 Sep - 29 Oct	China Airlines
28 Sep - 24 Oct	China Airlines
26 Sep - 26 Oct	China Airlines
25 Sep - 25 Oct	China Airlines
27 Sep - 24 Oct	STARLUX Airlines
02 Sep - 09 Sep	Air India
26 Sep - 28 Sep	China Airlines
30 Sep - 07 Oct	China Airlines
27 Sep - 28 Sep	China Airlines
27 Sep - 26 Oct	STARLUX Airlines
28 Sep - 25 Oct	Qatar Airways
26 Sep - 25 Oct	Alaska Airlines
27 Sep - 25 Oct	Alaska Airlines

Also check the deals for one-way flights from Ontario to Kathmandu 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 Ontario to Kathmandu in September from $1146

Return flights