Earlier on Thursday, the French World Cup winner was given the maximum penalty after non-endogenous testosterone was found in his system during a random drugs test on August 20.
Pogba first failed doping test came after Juventus' win over Udinese on the opening weekend of the Serie A season, after which he came off the bench in clashes with Bologna and Empoli.
During the September international break, news of Pogba's elevated testosterone levels first came to light, and the midfielder was provisionally suspended by Italy's National Anti-Doping Tribunal.
A second sample confirmed the abnormal levels of the hormone, although Pogba's agent Rafaela Pimenta affirmed that the former Manchester United man would never intentionally violate anti-doping policies.
Pogba has remained suspended over the last few months while prosecutors sought a maximum four-year ban for the Frenchman, who will not be eligible to return to competitive action until September 2027, taking into account the time he has already spent out of action.
Pogba - who will be 34 by the time his ban is lifted - confirmed the news on his Instagram page, saying in a story that he had "never knowingly or deliberately" taken a banned substance and would go to the Court of Arbitration for Sport to appeal his suspension.
"I have today been informed of the Tribunale Nazionale Antidoping's decision and believe that the verdict is incorrect," the 30-year-old wrote. "I am sad, shocked and heartbroken that everything I have built in my professional playing career has been taken away from me.
"When I am free of legal restrictions the full story will become clear, but I have never knowingly or deliberately taken any supplements that violate anti-doping regulations.
"As a professional athlete I would never do anything to enhance my performance by using banned substances and have never disrespected or cheated fellow athletes and supporters of any of the teams I have played for, or against. As a consequence of the decision announced today I will appeal this before the Court of Arbitration for Sport."
Juventus are yet to publicly respond to Pogba's four-year suspension, but the Old Lady are expected to terminate the midfielder's contract, which expires at the end of the 2025-26 campaign.
After departing Turin in a £89m deal for Manchester United in 2016, Pogba rejoined Juventus in the summer of 2022 following his exit from the Red Devils on a free transfer, having previously risen to prominence in Turin under Massimiliano Allegri, winning four Serie A titles.
However, the 30-year-old sustained a serious knee injury in pre-season ahead of the 2022-23 campaign and was kept waiting until February 2023 for his second debut for the Bianconeri, making 10 appearances in total last season.
Adductor and hamstring injuries also plagued Pogba during the back end of last season, where his only goal contribution was an assist for Federico Gatti in the first leg of their Europa League semi-final with Sevilla.
Pogba's serious knee issue saw him miss the 2022 World Cup, and the Frenchman earned his 91st and most recent cap for Les Bleus in a March 2022 friendly versus South Africa.