O'Kelly is a surname. Notable people with the surname include:
Aloysius O'Kelly (1853–1936), Irish painter, brother of James Joseph O'Kelly
Auguste O'Kelly (1829–1900), music publisher in Paris
Christopher O'Kelly (1895–1922), Canadian recipient of the Victoria Cross
Don O'Kelly (1924–1966), American actor
Edward Peter O'Kelly (1846–1914), Irish politician
Gabriel O'Kelly (died 1731), Irish clergyman
George O'Kelly (1831–1914), Franco-Irish pianist and composer
Henri O'Kelly (1859–1938), Franco-Irish composer, pianist and organist
James Joseph O'Kelly (1845–1916), Irish politician
John J. O'Kelly (1872–1957), Irish politician
Joseph O'Kelly (1828–1885), Franco-Irish composer and pianist
Malcolm O'Kelly (born 1974), Irish rugby player
Seán T. O'Kelly (1882–1966), Irish politician, second President of Ireland
Seumas O'Kelly (1881–1918), Irish writer
