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

Return flights

29 Dec - 21 Jan	Aer Lingus
07 Dec - 18 Dec	TAP
10 Dec - 14 Dec	Royal Air Maroc
10 Dec - 15 Dec	Scandinavian Airlines
10 Dec - 17 Dec	Royal Air Maroc
12 Dec - 19 Dec	Aer Lingus
29 Dec - 21 Jan	Brussels Airlines	direct
23 Dec - 24 Dec	Aer Lingus
25 Dec - 04 Jan	Frontier Airlines
23 Dec - 30 Dec	Aer Lingus
16 Dec - 19 Dec	Aer Lingus
29 Dec - 06 Jan	Brussels Airlines	direct
21 Dec - 30 Dec	Frontier Airlines
12 Dec - 19 Dec	Brussels Airlines	direct
19 Dec - 04 Jan	Frontier Airlines
25 Dec - 04 Jan	United	direct
17 Dec - 02 Jan	Lufthansa	direct
19 Dec - 04 Jan	United	direct

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 556€

Return flights