John Letts may refer to:

• John Letts (publisher) (1929–2006), English publisher, who founded the British Empire and Commonwealth Museum
• John Letts (mid-1700s), English stationary producer, who founded Letts of London
• John Spencer Letts (1934–2014), U.S. federal judge
• John Letts (jockey) (born 1943), former Australian jockey
• John Letts (tennis) (born 1964), former professional tennis player from the United States
• John Letts (RAF officer) (1897–1918), World War I flying ace in No. 48 Squadron RAF