The deal, reportedly worth £1.7m, also saw midfielder Soualiho Meite leave Monaco for Torino and was confirmed on Tuesday afternoon after Barreca had been in France for a medical.
Having come through the youth system at Torino, the 23-year-old made 39 appearances for their first-team in Serie A, while also spending two seasons out on loan at Cittadella and Cagliari.
But now, Barreca admitted he is ready to take the next step in his career.
— AS Monaco 🇲🇨 (@AS_Monaco) July 10, 2018
“I am very happy to sign with AS Monaco,” he told the club’s official website.
“AS Monaco has shown in previous seasons that he is a great European club. The project of the club is very ambitious, I am delighted to be part of it.
“I can not wait to start working with the staff and high quality players. I will give everything to improve and contribute to the team.”
Monaco are renowned for their work in bring through younger players, with the likes of Kylian Mbappe, Thomas Lemar, Bernardo Silva and James Rodriguez all impressing for the Principality side.
And Monaco Vice President Vadim Vasilyev believes the club can help guide Barreca on the right path.
“We are delighted to welcome Antonio Barreca to AS Monaco,” he said.
“Antonio is a young player, already experienced. We are confident that AS Monaco will help him find the conditions to further progress and help the club achieve its goals.”
Monaco’s transfer policy
In joining Monaco, Barreca became the club’s ninth signing of the summer – with only one being over the age of 21 – enhancing their reputation as a haven for young talent.
The club have already brought young defenders in in the shape of 17-year-old Jonathan Panzo from Chelsea and Ronael Pierre-Gabriel, 20, from Saint-Etienne.
At 16, Willem Geubbels and Robert Navarro are the youngest new acquisitions while Judilson Pele, 26, who joined from Portuguese side Rio Ave, is the only player older than 21.
Monaco have also signed Wilson Isidor, 17, Sofiane Diop, 18, and Samuel Grandsir, 21.