Hudson County is a county located in the U.S. state of New Jersey. As of the United States 2000 Census, the population was 608,975. Its county seat is Jersey City. It is part of the New York Metropolitan Area.

Hudson County lies several hundred feet from the western shore of Ellis and Liberty Islands, and has always been a gateway for many immigrants to the United States. Both Ellis Island and Liberty Island lie entirely within Hudson County's waters, which extend to the New York state line at the middle of the Hudson River. Liberty Island is wholly part of New York. Ellis Island is jointly administered by the states of New Jersey and New York. Nine-tenths of its land is technically part of Hudson County, with the remainder being part of New York[. Hudson County is also recognized as one of the Northeast's major transportation and industrial hubs.

Hudson County is the smallest of New Jersey's 21 counties.