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

Return flights

29 Sep - 09 Oct	Air Arabia
27 Sep - 04 Oct	Air Arabia
28 Sep - 05 Oct	Air Arabia
17 Sep - 18 Sep	Air Arabia
29 Sep - 01 Oct	Air Arabia
30 Sep - 01 Oct	Air Arabia
17 Sep - 24 Sep	Air Arabia
26 Sep - 02 Oct	Air Arabia
30 Sep - 10 Oct	Air Arabia
21 Sep - 28 Sep	Air Arabia
19 Sep - 28 Sep	Air Arabia
20 Sep - 27 Sep	Air Arabia
29 Sep - 30 Sep	Air Arabia
29 Sep - 09 Oct	Turkish Airlines	direct
28 Sep - 05 Oct	Turkish Airlines	direct
26 Sep - 02 Oct	Turkish Airlines	direct
19 Sep - 28 Sep	Turkish Airlines	direct

Also check the deals for one-way flights from Kathmandu to Istanbul 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 Kathmandu to Istanbul in September from 454€

Return flights