Mattrel played with Juventus for most of his career, between 1955 and 1965, aside from two brief loan spells with Anconitana and Palermo. With the Turin club, he won three Serie A titles during the 1957–58, 1959–60, and 1960–61 seasons, as well as three Coppa Italia tournaments in 1959, 1960, and 1965. After his time with Juventus, he spent two seasons with Cagliari, and one final season with SPAL before retiring in 1968. Throughout his career, he made 158 appearances in Serie A, 27 in the Coppa Italia, 4 in the European Cup, and 1 in the Cup Winners' Cup.