Gattellari was selected in the Australian team for the 1960 Summer Olympics in Rome, Italy. He defeated Abdelkader Belghiti from Morocco before losing to eventual gold medalist Gyula Török from Hungary. Gattellari made his professional debut on 18 September 1961.
On 2 December 1965 he contested the WBC flyweight world title, losing to Salvatore Burruni in the 13th round.
On 11 December 1967 Gattellari fought Lionel Rose for the Australian bantamweight title, losing by a knockout in the 13th round. He retired in 1968. Gattellari made a comeback in 1979, fighting Paul Ferreri for the Australian featherweight title.
He lost by a TKO in the 3rd round. Gattellari retired with a professional record of 21 wins (12 by knockout), three losses (all knockouts) and one draw.
Upon retirement Gattellari became a restaurateur, opening Berowra Waters Inn and then Rocky"s at Edgecliff.
He went on to become a finance broker. Gattellari contested the New South Wales state election, 1995 as a Liberal candidate for Cabramatta. He was defeated by Labor incumbent Reba Meagher.
Meagher sought an apprehended violence order against Gattellari when he used colourful language to describe his intention to defeat her.
Gattellari, Rocky (1989). The Rocky Road. William Heinemann Australia.
X. Retrieved 15 October 2010.