It is situated at the confluence of the Ripoll river and the Besós river, and very close to the northernmost neighbourhoods of the city of Barcelona and is therefore a part of the metropolitan area of Barcelona.

The municipality includes a small exclave to the north between Palau-solità i Plegamans and Mollet del Vallès.

The town is served by the A-7 autopista, the N-152 road, six Renfe Rodalies Barcelona and regional railway stations used by several lines, and the terminus Barcelona Metro line 11, located at Can Cuiàs.

The GR 92 long distance footpath, which roughly follows the length of the Mediterranean coast of Spain, has a staging point at Montcada i Reixac.

Stage 17 links northwards to Coll de la Font de Cera, a distance of 16.9 kilometres (10.5 mi), whilst stage 18 links southwards to Baixador de Vallvidrera station, a distance of 16.7 kilometres (10.4 mi).