John Barrett or Johnny Barrett may refer to:
- John Barrett (American football) (1899–1966), American football player
- John Barrett (athlete) (1879–1942), Irish track and field athlete
- John Barrett (Australian footballer) (1928–2023), Australian rules footballer
- John Barrett (cricketer) (born 1946), English cricketer
- John Barrett (ice hockey) (born 1958), Canadian NHL defenceman
- John Barrett (outfielder) (fl. 1872), American baseball outfielder
- John Barrett (tennis) (born 1931), English tennis player and commentator
- John Barrett (volleyball) (born 1962), Canadian volleyball player
- Johnny Barrett (American football) (1895–1974), American football player
- Johnny Barrett (baseball) (1915–1974), American baseball player
- John Barrett (actor) (1910–1983), British actor
- John Barrett (conservationist) (1913–1999), British conservationist, author and broadcaster
- John Barrett (diplomat) (1866–1938), United States ambassador to Siam, Argentina, Panama, and Colombia
- John Barrett (salon), the brand of beauty and hair salons by hairstylist John Barrett
- John Barrett, frontman of the band Bass Drum of Death
- John F. Barrett (born 1949), CEO of Western & Southern Financial Group