South Jersey comprises the southern portion of the U.S. state of New Jersey located between the lower Delaware River in the west and the Atlantic Ocean in the east. The designation of South Jersey with a distinct toponym is a colloquialism rather than an administrative definition and reflects geographical and perceived cultural and other differences between South Jersey and the northern part of the state. South Jersey is part of the Philadelphia metropolitan area, the seventh largest metropolitan region in the nation with 6.288 million residents in the core metropolitan statistical area and 7.366 million residents in the combined statistical area as of 2020.

Benjamin Franklin called the state "a barrel tapped at both ends". South Jersey may be defined geographically as the area below I-195 that includes the state's lower seven counties: Atlantic, Burlington, Camden, Cape May, Cumberland, Gloucester, and Salem. North Jersey is generally described as including the counties north of South Jersey that fall within the New York metropolitan area.

South Jersey and the wider Philadelphia metropolitan area have become a U.S. East Coast epicenter for logistics and warehouse construction, Salem County and the lower portion of and upper portion of Cumberland Counties additionally serve as residential communities for the petrochemical industry of New Castle County, Delaware. South Jersey shore communities, including Atlantic City and others in Atlantic and Cape May counties, have a distinct economy centered around the tourism industry. Burlington, Camden, and Gloucester counties have several older streetcar towns, and many residents from these three counties commute to Philadelphia, the nation's sixth most populous city, which is located immediately west of South Jersey across the Delaware River, accessible by the Benjamin Franklin Bridge, Betsy Ross Bridge, and Walt Whitman Bridge.