John Mansfield may refer to:

• John Mansfield (Beverley MP), member for Beverley (UK Parliament constituency) in 1593
• John Mansfield (American politician) (1822–1896), American soldier and politician
• John Mansfield (English politician) (1889–1970), British trade unionist and politician
• Sir John Mansfield (Royal Navy officer) (1893–1949), British admiral
• John Mansfield (footballer) (born 1946), English footballer
• John Mansfield (judge) (born 1946), Australian judge
• John Mansfield School, a school in the Dogsthorpe area of Peterborough, England, 1957–2007