The victim has been identified as Charles A. McKinney, Jr., 37, of Newark.
He was shot at about 12:39 p.m. Monday while in a car in the 200 block of 21st Street in Irvington.
McKinney was transported to University Hospital where he was pronounced dead.
Prosecutors are investigating whether the shooting may have been related to a robbery.
Anyone with information is urged to contact the Essex County Prosecutor's Office tips line at 1-877-7432.