Lawrence Brook is a tributary of the Raritan River in Middlesex County, New Jersey, in the United States.

Its lowest section, near the Raritan River, is tidal; it hosts marine wildlife and is regarded as a coastal area.

Its drainage basin, the Lawrence Brook watershed, is a 40-square-mile (100 km2) area, identified by the USGS code HUC 02030105130.

Lawrence Brook is a wildlife corridor, a bird migration area and a highly sensitive body of water.

The Lawrence Brook, a 30-mile inland waterway (New Jersey), connects from the Raritan Bay to the lesser known end; splitting apart into two branches in South Brunswick, this is a list of important landmarks in Central New Jersey where the Lawrence Brook is present (sometimes in larger water-body forms).