The start of De Ligt's Juve career has not been easy since his move from Ajax, but the Netherlands centre-back had a moment to remember in the 70th minute of a bad-tempered clash on Sunday (AEDT).
Juve had been unable to break the deadlock but when Gonzalo Higuain knocked a corner into his path, De Ligt showed a striker's instinct to break Salvatore Sirigu's resistance.
Victory moved Juve back to the top of the Serie A table above Inter Milan, with the Bianconeri now having won on 10 of their past 11 league visits to Torino.
With Walter Mazzarri seeking his first win over Juventus since 2011, handball appeals were rejected in both penalty areas during a stodgy opening.
Juve took until the 32nd minute to create a clear chance, Paulo Dybala dancing into the box but placing his shot too close to Sirigu, the Torino goalkeeper then making a comfortable save to keep out Cristiano Ronaldo's snapshot.
The pressure in Torino's box grew in the minutes before half-time, Sirigu showing strong reactions when Matthijs de Ligt diverted Ronaldo's cross-shot at goal.
Sirigu made another smart stop to keep out Ronaldo in the 56th minute, diving low to his right, before Maurizio Sarri replaced Dybala with Higuain.
The substitute's stunning volley was tipped on to the crossbar in sensational fashion by Sirigu, but the goalkeeper was beaten from the resulting corner as De Ligt turned home from close range.
Wojciech Szczesny prevented Cristian Ansaldi giving the hosts a rapid response as Juve closed out yet another derby victory to pile more pain on Torino, which had a stoppage-time equaliser from Bremer rightly ruled out for offside.