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

Return flights

29 Sep - 06 Oct	Air Arabia
21 Sep - 05 Oct	Air Arabia
20 Sep - 04 Oct	IndiGo
26 Sep - 04 Oct	IndiGo
01 Sep - 13 Sep	IndiGo
17 Sep - 22 Sep	IndiGo
16 Sep - 21 Sep	IndiGo
12 Sep - 27 Sep	IndiGo
11 Sep - 26 Sep	IndiGo
29 Sep - 06 Oct	Turkish Airlines	direct
21 Sep - 05 Oct	Turkish Airlines	direct
26 Sep - 04 Oct	Turkish Airlines	direct
16 Sep - 21 Sep	Turkish Airlines	direct
01 Sep - 13 Sep	Turkish Airlines	direct
12 Sep - 27 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 476€

Return flights