AirHint found the following cheapest return flights from Washington (IAD) to Brussels (BRU) in December 2025 (see full year).

Return flights

11 Dec - 18 Dec	Icelandair
31 Dec - 10 Jan	Scandinavian Airlines
07 Dec - 16 Dec	Icelandair
11 Dec - 21 Dec	Icelandair
29 Dec - 21 Jan	Aer Lingus
12 Dec - 18 Dec	Aer Lingus
26 Dec - 17 Jan	Aer Lingus
12 Dec - 22 Dec	TAP
14 Dec - 28 Dec	TAP
11 Dec - 22 Dec	TAP
29 Dec - 06 Jan	SWISS
17 Dec - 06 Jan	Icelandair
15 Dec - 22 Dec	Aer Lingus
16 Dec - 10 Jan	Frontier Airlines
17 Dec - 10 Jan	Icelandair
12 Dec - 21 Dec	Aer Lingus
13 Dec - 20 Dec	Aer Lingus
13 Dec - 17 Jan	Aer Lingus
31 Dec - 10 Jan	Brussels Airlines	direct
02 Dec - 03 Jan	TAP

Also check the deals for one-way flights from Washington to Brussels 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 Washington to Brussels in December from $474

Return flights