Pettit is an English surname of Hiberno-Norman origin. Variant spellings include Pettitt and Petitt. People with the surname include:
- B. R. Pettit (1947–2006), American sculptor
- Catriona Pettit (born 1971), Australian television presenter
- George Pettit (born 1982), Canadian vocalist
- Alex Pettit (born 1986), American computer scientist, professor, and vocalist
- Lloyd Pettit (1927–2003), American sportscaster
- Thomas S. Pettit (1843–1931), newspaper publisher and politician from Kentucky
- Tom Pettit (1931–1995), American television news correspondent
- Becky Pettit (born 1970), American sociologist
- Donald Pettit (born 1955), American astronaut
- Edison Pettit (1889–1962), American astronomer
- Joseph M. Pettit (1916–1986), American academic
- Katherine Pettit (1868–1936), American educator
- Mary DeWitt Pettit (1908–1996), American physician
- Philip Pettit (born 1945), Irish philosopher and political theorist
- Rowland Pettit (1927—1981), American chemist
- Steve Pettit, (born 1955), President of Bob Jones University
- Charles Pettit (1736–1806), American lawyer and merchant
- Daniel Pettit (1915–2010), English footballer and industrialist
- Gabrielle Petit (feminist) (1860–1952), French feminist activist, anticlerical, libertarian socialist, newspaper editor
- Jane Bradley Pettit, American philanthropist
- Lyman C. Pettit (1868–1950), American pastor
- Robert Lee Pettit (1906–1941), American naval enlisted man; recipient of the Navy Cross
- William H. Pettit (1885–1985), New Zealand Christian missionary