John Agnew may refer to:
- John Agnew (Prince Edward Island politician) (1854–1928), a merchant and politician from Prince Edward Island, Canada
- John Agnew (New Brunswick politician) (d. 1812), a Loyalist minister and politician in New Brunswick
- John Hume Agnew (1863–1908), former Provincial Treasurer for Manitoba, Canada
- John A. Agnew (born 1949), British-American political geographer
- John Stuart Agnew (born 1949), British MEP