Born in Caderzone, Italy, the Sartoris moved to Manchester when Carlo was a child, and he grew up in the Collyhurst area of the city.
He came through the Manchester United youth team in the mid-1960s and was one of the first non-British players to come up through the junior ranks at the club. He signed as an apprentice with the club in July 1963, at the age of 15, turned professional at the age of 17, and made his debut for the club in October 1968, coming on as a substitute for Francis Burns in a 2–2 away draw against Tottenham Hotspur, becoming the club's very first foreign player.
He left in 1973, with a total of 55 appearances and 6 goals for Manchester United, and returned to Italy to sign for Bologna. He would later play for Lecco, SPAL 1907, Rimini and Trentino before retiring in 1984.