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

Return flights

26 Sep - 29 Sep	Korean Air
22 Sep - 29 Sep	Korean Air
25 Sep - 29 Sep	Korean Air
21 Sep - 24 Sep	Korean Air
22 Sep - 26 Sep	Korean Air
28 Sep - 15 Oct	Korean Air
21 Sep - 28 Sep	Korean Air
18 Sep - 22 Sep	Korean Air
19 Sep - 22 Sep	Korean Air
19 Sep - 25 Sep	Korean Air
19 Sep - 26 Sep	Korean Air
27 Sep - 26 Oct	Korean Air
28 Sep - 02 Oct	Korean Air
19 Sep - 18 Oct	Korean Air
28 Sep - 05 Oct	Korean Air
18 Sep - 01 Oct	Korean Air
25 Sep - 03 Oct	Korean Air
30 Sep - 03 Oct	Korean Air
26 Sep - 01 Oct	Korean Air
30 Sep - 13 Oct	Korean Air

Also check the deals for one-way flights from Ontario 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 Ontario to Bangkok in September from $696

Return flights