Martinsville is a city located in the New Jersey region of the United States. During the most recent census, Martinsville had a population of 11,980. Martinsville is the 144th most poplulated city in the New Jersey region, the 3,444th most populated city in the United States and the 18,983rd most populated city in the world. Martinsville is in the America/New York timezone which is 4 hours behind UTC. Martinsville adjusts the hour with daylight savings time during the winter months.