Diniz is a Portuguese-language surname. It may refer to:
Denis of Portugal (1261–1325), the sixth King of Portugal and the Algarve
Abilio Diniz (born 1936), Brazilian businessman, father of Pedro
Alex Diniz (born 1985), Brazilian cyclist
Gabriel Diniz (1990–2019), Brazilian singer and composer
Jacinto F. Diniz (1888–1949), American politician
Mauro Diniz (born 1952), Brazilian cavaquinist and singer
Paulo Diniz (1940–2022), Brazilian singer
Paulo Roberto Diniz Jr. (fl. 1990s–2010s), Brazilian bass guitarist
Pedro Diniz (born 1970), Brazilian racing driver, son of Abílio
Priscillo Diniz (born 1948), Brazilian golfer
Fernando Diniz (born 1974), Brazilian football coach
Yohann Diniz (born 1978), French race walker
