Delong or DeLong is a surname. Notable people with the surname include:
Alana DeLong, Canadian politicianDelmar DeLong, American politicianDing Delong, military officerGary DeLong, American soccer playerGeorge W. DeLong (1844–1881), United States Navy officer and explorerJ. Bradford DeLong (born 1960), economistJesse Delong (1805–1868), Canadian politicianJia Delong (born 1985), baseball playerJoe DeLong (born 1972), American (West Virginian) politicianKeith DeLong (born 1967), football playerMahlon DeLong, American neurologistMichael Delong, American military officerRichard DeLong, Sacred Harp singingRussell V. DeLong (1901–1981), minister and college presidentSidney Randolph DeLong (1875–1914), American politicianSolomon DeLong (1849–1925), writer and journalistSophie Delong (born 1957), French politicianSteve DeLong (1943–2010), American football player