[3][4] Gabriel Sandu was born in Bucharest on 7 November 1952 and started playing football at Metalul București.
[1][5] Afterwards, he went to play for Dinamo București, making his Divizia A debut on 2 May 1971 in a 1–0 victory against Argeș Pitești, winning the title in his first season spent at the club, coaches Nicolae Dumitru and Traian Ionescu giving him nine appearances, also reaching the 1971 Cupa României final where he played in the first half of the 3–2 loss with rivals Steaua București, being replaced for the second with Mircea Stoenescu.
[1][5][6][7] He won three more titles with The Red Dogs, in the first worked with coach Ion Nunweiller who used him in 28 games, in the second he played 25 games and scored two goals under the guidance Dumitru and in the third he worked again with Nunweiller, making 29 appearances in which he scored once in a 4–2 victory against Steaua.
[1][5][9][10] After spending nine seasons at Dinamo, Sandu went to play for Progresul București, where he ended his career after making 19 appearances in the league, his last Divizia A match taking place on 30 October 1981 in a 1–0 victory against Politehnica Timișoara, having a total of 211 appearances with four goals scored in the competition.
[1][5] Gabriel Sandu played 17 games at international level for Romania, making his debut on 5 June 1974 under coach Valentin Stănescu in a friendly which ended 0–0 with Netherlands.