AirHint found the following cheapest return flights from Seattle (SEA) to Istanbul (IST) in December 2025 (see full year).

Return flights

29 Dec - 16 Jan	KLM
29 Dec - 16 Jan	Turkish Airlines	direct
15 Dec - 22 Dec	KLM
10 Dec - 17 Dec	Icelandair
27 Dec - 10 Jan	Air France
16 Dec - 22 Dec	Air France
27 Dec - 10 Jan	Turkish Airlines	direct
29 Dec - 03 Jan	Icelandair
17 Dec - 28 Dec	Alaska Airlines
24 Dec - 01 Jan	Icelandair
23 Dec - 01 Jan	Frontier Airlines
26 Dec - 04 Jan	Lufthansa
14 Dec - 01 Jan	Aer Lingus
10 Dec - 17 Dec	Turkish Airlines	direct
15 Dec - 29 Dec	Lufthansa
16 Dec - 17 Dec	Hawaiian Airlines
18 Dec - 20 Dec	Qatar Airways
24 Dec - 02 Jan	Icelandair
16 Dec - 22 Dec	Turkish Airlines	direct
21 Dec - 28 Dec	Delta

Also check the deals for one-way flights from Seattle to Istanbul in December.

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 Seattle to Istanbul in December from 626€

Return flights