Vallensbæk Municipality is a municipality in the Capital Region of Denmark on Zealand. It is part of the Greater Copenhagen area and consist primarily of the suburb of Vallensbæk. It is one of the smallest municipalities in Denmark in terms of area. Vallensbæk Municipality borders the municipalities of Ishøj, Høje-Taastrup, Albertslund and Brøndby. It borders Køge Bay, and the Køge Bay Beach Park along the coast. The suburb of Vallensbæk consists of two sections, not directly connected to each other: Vallensbæk Nordmark in the north and Vallensbæk Strand in the south. The two parts of the town are commonly referred to together as Vallensbæk. The only other settlement in the municipality is the village of Vallensbæk Landsby.

The urban area of Copenhagen, lying mostly in the Capital Region of Denmark but also in Region Zealand, consist of Copenhagen and Frederiksberg municipalities and the former Copenhagen County. In all, it consists of 18 municipalities, and except parts of Ballerup, Greve, Ishøj, former Søllerød and former Værløse, mentioned with their population included from 2007. Ishøj and Greve Strand are included for the first time since 1999. As of 1 January 2022, this area had a population of 1,336,982. Statistics Denmark states that the definition of the urban area is based on UN's 200m definition.