John O'Farrell may refer to:
John O'Farrell (author) (born 1962), British author, broadcaster and political campaigner John O'Farrell (politician) (1826–1892), Canadian politician John O'Farrell (venture capitalist), Irish American venture capitalist John A. O'Farrell (1823–1900), Irish American adventurer, miner
See also J. T. O'Farrell (died 1971), Irish politician and trade union official John Farrell (disambiguation)