After winning the Giro della Valle d´Aosta in 1963, he switched to the Professionels as a relatively unknown youngster at the age of 21 and already had seven first places in the first year of his professional career, including the Trofeo Baracchi couple time trial (with Fornoni) and the classic Lombardy - Fought for the tour. He achieved his greatest successes in stage races by winning the overall ranking of the Giro d'Italia in 1966, the Tour de Suisse in 1967 and twice the Tour de Romandie (1966, 1971).
He contested the Giro d`Italia seven times and won six stages. As a professional novice in 1964, he was already fifth, 1966 first, in 1967 and 1968 sixth and in 1973 tenth. In 1971 and 1972 he had to give up prematurely. In the Tour de France he started twice and was able to take third place in the overall standings in 1965, while in 1971 he had to retire as a helper to Gimondi. In Italy he was one of the most famous drivers of his time and from 1965 to 1968 he was the captain of the Molteni racing team. He celebrated a total of 85 victories, was able to win the Italian semi-classic Giro dell Emilia three times, the Giro dell Apennino twice and Milan-Turin, the Giro dell Umbria, and Giro di Romagna once. In 1967, Motta was only narrowly beaten by Eddy Merckx in the sprint at the spring classic Milan-San Remo. In 1968 he was disqualified after the Giro d'Italia for doping with amphetamines.
Motta was not only a strong stage driver, but also successful in six-day races. At the "Sei Giorni dell Milano" he was able to win four times: in 1965 with Rik van Steenberghen and in 1966, 1967 and 1968 with Peter Post. In 1971 in Montreal, Canada, he took first place alongside Briton Tony Gowland. In his last season, 1974, he was able to win three loops and ended his professional career with a total of 85 victories in road races. However, Motta returned briefly in 1976 when he was supposed to contest the Giro d`Italia for the GBC-TV Color team.