The 29-year-old only returned to San Siro at the end of last season having made 10 appearances for West Ham in the Premier League, and it may be some time before he pulls on the Milan shirt again.
With competition for places high in midfield, Nocerino has been deemed surplus to requirements by new head coach Filippo Inzaghi, and Torino have moved quickly to secure his signature.
His temporary move to Turin was confirmed on Torino's official website on Wednesday, although no details regarding the length of the loan were disclosed.
Nocerino has gradually fallen out of favour at Milan since his move from Palermo in 2011.
He made 61 league appearances in two seasons but only made 11 last term, and now faces a second spell away from the club.
Torino finished seventh in Serie A last season and claimed a place in the UEFA Europa League after Parma were not granted a licence to compete in European competition.