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

Return flights

02 Dec - 09 Dec	Icelandair
07 Dec - 14 Dec	Icelandair
12 Dec - 19 Dec	Icelandair
03 Dec - 10 Dec	Icelandair
15 Dec - 19 Dec	Icelandair
08 Dec - 15 Dec	Icelandair
16 Dec - 26 Dec	Icelandair
17 Dec - 24 Dec	Icelandair
13 Dec - 20 Dec	Icelandair
18 Dec - 25 Dec	Icelandair
25 Dec - 04 Jan	Icelandair
28 Dec - 04 Jan	Icelandair
27 Dec - 03 Jan	Icelandair

Also check the deals for one-way flights from Seattle to Copenhagen 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.

Book a cheap hotel in Copenhagen

Cheap car rent in Copenhagen

Cheapest return flights from Seattle to Copenhagen in December from 379€

Return flights