At international level, he was a member of the Italy national team that won UEFA Euro 1968.

He played club football for three Italian clubs throughout his career: Legnano, Triestina, and most prominently with Juventus, where he won several domestic titles, also serving as the team's captain.

At international level, Castano also played for the Italy national team on seven occasions between 1959 and 1969, winning the 1968 UEFA European Championship on home soil.

[1] On 3 July 1968, Castano founded the Italian Footballers' Association (AIC), in Milan, along with a number of fellow players including Giacomo Bulgarelli, Sandro Mazzola, Gianni Rivera, Giancarlo De Sisti, and Giacomo Losi.

The recently retired Sergio Campana, also a lawyer, was appointed president of the association.