Castagnoli is an Italian surname. Notable people with the surname include:
Claudio Castagnoli (born 1980), Swiss professional wrestler Ferdinando Castagnoli (1917–1988), Italian topographer Giulio Castagnoli (born 1958), Italian composer Giuseppe Castagnoli (1754–1832), Italian painter Paola Ricciardi-Castagnoli (born 1948), Italian immunologist Ubaldo Castagnoli (1902–1982), Italian architect and engineer
See also Castagnoli, Gaiole in Chianti, village in Tuscany