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

Return flights

03 Dec - 12 Dec	Icelandair
02 Dec - 11 Dec	Lufthansa
04 Dec - 10 Dec	British Airways
29 Dec - 24 Jan	Lufthansa
03 Dec - 08 Dec	British Airways
04 Dec - 23 Dec	Delta
06 Dec - 08 Jan	British Airways
29 Dec - 24 Jan	Turkish Airlines	direct
15 Dec - 22 Dec	British Airways
03 Dec - 08 Dec	Turkish Airlines	direct
06 Dec - 27 Dec	KLM
14 Dec - 21 Dec	Lufthansa
12 Dec - 19 Dec	Frontier Airlines
16 Dec - 10 Jan	Icelandair
15 Dec - 10 Jan	KLM
18 Dec - 10 Jan	WestJet
17 Dec - 10 Jan	Hawaiian Airlines
11 Dec - 03 Jan	WestJet
24 Dec - 02 Jan	Frontier Airlines
23 Dec - 01 Jan	Alaska Airlines

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 $438

Return flights