Robertsville is a census-designated place and unincorporated community in Marlboro Township, Monmouth County, in the U.S. state of New Jersey.

[3] Robertsville is in northern Monmouth County, in the western corner of Marlboro Township.

U.S. Route 9 passes through the west side of the community, leading south 6 miles (10 km) to Freehold Borough, the Monmouth county seat, and north 9 miles (14 km) to South Amboy.

The New Jersey Route 18 expressway runs along the eastern side of Robertsville, with access to the community from Exit 29 (Tennent Road).

There were 3,941 housing units at an average density of 665.8 per square mile (257.1/km2).