San Lorenzo completed the signing of Miguel Russo as manager on Thursday, agreeing to a deal that runs until December 2025.
Russo replaces Leandro Romagnoli, who stepped down last Sunday after a bad run of results.
"The Russo era has begun," the Buenos Aires club said in a social media post that included video footage of the 68-year-old's first training session in charge.
Russo, who was also San Lorenzo's manager in 2008 and 2009, had been out of work since parting ways with Rosario Central in August.
The first match of his new spell will be a home clash against Barracas Central in Argentina's Primera Division on Sunday.