John Greeley Jenkins (8 September 1851 – 22 February 1923) was an American-Australian politician. He was Premier of South Australia from 1901 to 1905. He had previously served as Minister for Education and the Northern Territory and Commissioner for Public Works under Thomas Playford II, Commissioner of Public Works under Charles Kingston and Chief Secretary under Frederick Holder. He was subsequently Agent-General for South Australia from 1905 to 1908.