The incident happened around 7:30 p.m. Friday in the area of Park Way and Rogers Avenue in Hightstown.
According to the prosecutor's office, the 34-year-old woman told police it happened while she was walking.
The victim said she was physically and sexually assaulted after she was approached from behind by an unknown man, investigators said.
No arrests have been made and no suspects have been identified.
Anyone with any information on the incident or who has had a similar encounter is asked to contact SVU Sgt. Sherika Salmon at (609) 960-3119 or Detective Natalie Martinez at (609) 331-4318. Tips can also be submitted anonymously online at mercercountyprosecutor.com/tips.