Longfield is an English surname. Notable people with the surname include:
Cynthia Longfield (1896–1991), Irish entomologist and explorer
Judi Longfield (born 1947), Canadian politician
Richard Longfield (1802–1889), Irish politician
Richard Longfield, 1st Viscount Longueville (1734–1811), Irish politician
Robert Longfield, American composer
Samuel Mountiford Longfield (1802–1884), Irish lawyer and economist