The 3rd New Jersey Volunteer Infantry was an American Civil War Union Army regiment of infantry from New Jersey that served in the Army of the Potomac. It was recruited and mustered into Federal service in May 1861, and was brigaded with the 1st New Jersey Volunteer Infantry, the 2nd New Jersey Volunteer Infantry, and the 4th New Jersey Volunteer Infantry to make up what became famed as the "First New Jersey Brigade". The regiment and brigade served as the 1st Brigade of the 1st Division of the VI Corps, and participated in numerous battles from the June 27, 1862, Battle of Gaines Mill, Virginia, to the final Union assaults on Confederate positions at Petersburg, Virginia, in April 1865.