The Benelux Union (Dutch: Benelux Unie; French: Union Benelux; Luxembourgish: Benelux-Unioun), also known as simply Benelux, is a politico-economic union and formal international intergovernmental cooperation of three neighbouring states in western Europe: Belgium, the Netherlands, and Luxembourg. 

The name Benelux is a portmanteau formed from joining the first few letters of each country's name—Belgium, Netherlands, Luxembourg—and was first used to name the customs agreement that initiated the union (signed in 1944). It is now used more generally to refer to the geographic, economic, and cultural grouping of the three countries.

The Benelux is an economically dynamic and densely populated region, with 5.6% of the European population (29.2 million residents) and 7.9% of the joint EU GDP (EUR 36,000/resident) on no more than 1.7% of the total surface of the EU.

Some examples of results of Benelux cooperation: automatic level recognition of all diplomas and degrees within the Benelux, a new Benelux Treaty on Police cooperation, common road inspections and a Benelux pilot with digital consignment notes.

The main institutions of the Union are the Committee of Ministers, the Council of the Union, the General Secretariat, the Interparliamentary Consultative Council and the Benelux Court of Justice while the Benelux Office for Intellectual Property cover the same territory but are not part of the Benelux Union.

The Benelux General Secretariat is located in Brussels. It is the central platform of the Benelux Union cooperation. It handles the secretariat of the Committee of Ministers, the Council of Benelux Union and the various committees and working parties. The General Secretariat provides day-to-day support for the Benelux cooperation on the substantive, procedural, diplomatic and logistical levels. The Secretary-General is Alain de Muyser from Luxembourg and there are two deputies: Deputy Secretary-General Frank Weekers from the Netherlands and Deputy Secretary-General Rudolf Huygelen from Belgium.

The presidency of the Benelux is held in turn by the three countries for a period of one year. Belgium hold the presidency for 2021.