Lower Berkshire Valley is a census-designated place (CDP) in Roxbury and Jefferson townships, Morris County, New Jersey, in the United States. As of the 2020 census, it had a population of 617.
The community is in western Morris County, primarily in the northeast part of Roxbury Township, along Berkshire Valley Road. The northernmost part of the CDP is in southern Jefferson Township. Interstate 80 passes through the southern part of the CDP, but with no direct access. The community is northwest of Wharton and northwest of Dover.
According to the U.S. Census Bureau, the Lower Berkshire Valley CDP has a total area of , of which , or 2.23%, are water. The area is drained by the Rockaway River, which passes just east of the CDP boundary and flows east to the Passaic River at the Essex County border.
Lower Berkshire Valley was first listed as a census designated place in the 2020 U.S. census.