O'Kelly is a surname. Notable people with the surname include:
Aloysius O'Kelly (1853–1936), Irish painter, brother of James Joseph O'KellyAuguste O'Kelly (1829–1900), music publisher in ParisChristopher O'Kelly (1895–1922), Canadian recipient of the Victoria CrossDon O'Kelly (1924–1966), American actorEdward Peter O'Kelly (1846–1914), Irish politicianGabriel O'Kelly (died 1731), Irish clergymanGeorge O'Kelly (1831–1914), Franco-Irish pianist and composerHenri O'Kelly (1859–1938), Franco-Irish composer, pianist and organistJames Joseph O'Kelly (1845–1916), Irish politicianJohn J. O'Kelly (1872–1957), Irish politicianJoseph O'Kelly (1828–1885), Franco-Irish composer and pianistMalcolm O'Kelly (born 1974), Irish rugby playerSeán T. O'Kelly (1882–1966), Irish politician, second President of IrelandSeumas O'Kelly (1881–1918), Irish writer