Middelharnis (Dutch pronunciation: [ˌmɪdəlˈɦɑrnɪs] ⓘ) is a town and former municipality in the western Netherlands, in the province of South Holland, on the island of Goeree-Overflakkee.

On 1 January 2013, Middelharnis merged with Goedereede, Dirksland, and Oostflakkee into the new municipality of Goeree-Overflakkee.

In 1598, a fish auction was built in Middelharnis and it developed into a regional centre.

[4] The former town hall is a prominently situated neoclassic building with ridge turret built between 1639 and 1640.

This shopping center settled itself on a dike which used to be the last barrier for the town from the Haringvliet.