Johann Philipp Gerlach (24 July 1679 – 17 September 1748) was a Prussian court architect, who built churches and public buildings in and around Berlin.
Gerlach was born in Spandau. In 1707, he succeeded Martin Grünberg as royal director of building (königlicher Baudirektor und Leiter des Bauwesens) in Berlin. King Frederick William I of Prussia promoted him to Oberbaudirektor der königlichen Residenzen in 1720, making him responsible for all building of the state including bridges and fortifications. Gerlach directed the remodelling of the Kronprinzenpalais in 1733, and built the Kollegienhaus/Kammergericht in 1734/35.
He also designed three mayor squares in Friedrichstadt: Pariser Platz (Quarree), Leipziger Platz (Oktogon) and Mehringplatz (Rondell). The Garnisonkirche in Potsdam was his major work as an architect. Its ruin was demolished in 1963.
He retired in April 1737 for health reasons, succeeded by . He died in Berlin.