Midden-Delfland () is a municipality (gemeente) in the Westland region in the province of South Holland in the Netherlands. It had a population of in , and covers an area of of which is water.
It was formed on 1 January 2004 through the merger of the former municipalities:
The municipality comprises the population centres:
The green area that comprises the municipality of Midden-Delfland was named Midden-Delfland before 2004, and it referred to the green area surrounded by cities (such as The Hague and Rotterdam) and the horticulture area of Westland. The supporters of a continuous green area were lucky that the municipality of Midden-Delfland became a reality: the cities of Delft, Vlaardingen and Schiedam wanted to build new houses here, and the Westland gardeners also wanted to expand. Now, Midden-Delfland is designated as a recreation area for people from the surrounding cities.