Middlebush is an unincorporated community and census-designated place (CDP) located in Franklin Township, in Somerset County, New Jersey, United States. As of the 2010 United States Census, the CDP's population was 2,326. It is perhaps most distinguished as being the host section for Franklin Township's municipal complex. Middlebush still has a rural feel with 19th-century homes and tree-lined streets. Middlebush was once a stop on the Millstone and New Brunswick Railroad, and this legacy is evident in the street named Railroad Avenue that presently has no railroad tracks in sight.