Vallès Occidental (Catalan pronunciation: [bəˈʎɛz uksiðənˈtal]) is a comarca (county) in the Barcelona region in Catalonia (Spain).

East of that axis, the watershed of the Besòs includes the rivers Ripoll and Caldes, (the latter forming the eastern border of the comarca).

Vallès Occidental has several notable official hiking trails, known as "senders de gran recorregut".

The most important industries are textiles, mechanical engineering, metallurgy, machinery, electrical equipment, construction, chemicals, paper, and the processing of food products.

An industrial crisis at the end of the 1970s and the beginning of the 1980s led to a greater importance for the commercial and service sectors, especially computer-related work.