On 20 January 1961, Benvenuti made his professional boxing debut, beating Ben Ali Allala by decision in six rounds. He then won 29 fights in a row before challenging for the Italian middleweight title, on 1 March 1963, in Rome against Tommaso Truppi. His winning streak extended to 30 when he knocked out Truppi in round eleven. His winning streak reached 46 wins in a row when he met former world junior middleweight champion
Denny Moyer on 18 September 1964, beating Moyer on points in ten rounds. After reaching 55 wins in a row, including a five-round knockout of Truppi in a rematch, he met world jr. middleweight champion
Sandro Mazzinghi in
Milan, on 18 June 1965. This was a fight the Italian public clamoured for: both men were Italian, both men claimed to be the best in their division, and they had expressed the desire to fight each other. Benvenuti became the world junior middleweight champion with a sixth-round knockout win. It was common, in that era, for world champions to fight for regional belts after winning the world title, so on 15 October 1965, he added the European belt at the middleweight division, with a sixth-round knockout of Luis Folledo. A rematch with Mazzinghi took place on 17 December 1965, and Benvenuti retained the world junior middleweight crown after winning a fifteen-round decision. After three non-title wins, including a twelve-round decision over
Don Fullmer and a fourteen-round knockout in West Germany of Jupp Elze (Benvenuti's first professional fight abroad), he travelled to
South Korea, where he lost his world junior middleweight title to
Ki-Soo Kim, who won by decision in fifteen rounds on 25 June 1966, breaking Benvenuti's record of 65 consecutive wins. Frustrated by what he perceived as an unjust decision to favour the local boxer, Benvenuti decided to drop the junior middleweight and concentrate on the
middleweight division instead. On a rematch at
Shea Stadium on 29 September 1967, he lost by a decision in fifteen rounds. but chose to continue fighting "like a cripple" rather than quit. The most curious defence of Benvenuti's active reign, took place on 4 October 1969, when he retained the world middleweight title with a seven-round disqualification win over American
Fraser Scott at the Stadio S. Paolo in Naples. From the first round, Scott was warned repeatedly, and with increasing intensity from the referee, about attempted butting. Scott, a young fighter unschooled in the European insistence on what his trainer referred to as "that...Olympic stand-up style", knowing only the battle plan he went in with and speaking no Italian, did not understand the warnings at first, then was unable to alter his approach; to the American, he was merely "ducking" Benvenuti's shots. The bout was foul-filled even without this added controversy; Scott would later accuse Benvenuti of having tried to thumb him, and during the sixth round, the fighters' legs became entangled as they wrestled, causing both to crash to the canvas. Round seven saw the stoppage, the referee asserting "attempted butting", Fraser Scott and corner forever insisting he had "ducked". On 22 November 1969, Benvenuti beat former world welterweight champion
Luis Rodriguez by knockout in 11 rounds and once again retained his world middleweight title. On 13 March 1970, in a non-title bout, Benvenuti was knocked out in the eighth round by unknown American
Tom Bethea in Australia. The upset defeat caused Bethea to earn a world title shot at Benvenuti's title. Benvenuti avenged the defeat when the two met again in
Umag with an eighth-round knockout. On 7 November 1970, Benvenuti lost his title in Rome after being knocked out in round twelve by rising star
Carlos Monzón. In 1971, after losing a ten-round decision to José Chirino, a fighter he had picked due to his fighting style's similarities with Monzón, Benvenuti got a rematch with Monzón for the world middleweight title in
Monte Carlo on 8 May 1971. Monzón won again in round three when Benvenuti's corner threw in the towel. Realizing that he no longer had the stamina to compete with champions of a new generation like Monzón, Benvenuti announced his retirement. Benvenuti had a record of 82 wins, 7 losses and 1 draw (tie) in 90 professional boxing bouts, with 35 wins by
knockout. In 1992, he was inducted into the
International Boxing Hall of Fame. ==Post-boxing==