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

Return flights

04 Dec - 11 Dec	Icelandair
09 Dec - 12 Dec	Scandinavian Airlines
10 Dec - 15 Dec	Delta
16 Dec - 13 Jan	Aer Lingus
01 Dec - 05 Dec	TAP
29 Dec - 21 Jan	Aer Lingus
26 Dec - 17 Jan	KLM
02 Dec - 27 Dec	Turkish Airlines
15 Dec - 10 Jan	Frontier Airlines
17 Dec - 28 Jan	Aer Lingus
17 Dec - 13 Jan	Aer Lingus
30 Dec - 06 Jan	Turkish Airlines
26 Dec - 10 Jan	TAP
14 Dec - 21 Dec	Aer Lingus
16 Dec - 10 Jan	Aer Lingus
29 Dec - 06 Jan	Icelandair
13 Dec - 20 Dec	Aer Lingus
16 Dec - 23 Dec	British Airways
09 Dec - 16 Dec	British Airways
21 Dec - 27 Dec	Aer Lingus

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 376€

Return flights