The France international, 30, was provisionally suspended in September after a drugs test found elevated levels of testosterone in his system.
"Everything I have built in my professional career has been taken away from me," he said in a statement.
The former Manchester United player added he would appeal.
Pogba was randomly tested after Juventus' first match of the season on 20 August.
The positive test was confirmed by Italy's national anti-doping tribunal in a second sample in October, and the anti-doping prosecutor's office requested a four-year suspension.
Juventus told the BBC they received notification from the anti-doping tribunal on Thursday morning.
Pogba said he believed the verdict was "incorrect" and he would "never knowingly or deliberately" dope.
"When I am free of legal restrictions, the full story will become clear," he said.
"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."
The ruling means Pogba will be unable to play until 2027, when he will be 34, with the ban backdated to the date of the failed test.
Speaking at the time of the initial suspension, Pogba's agent, Rafaela Pimenta, said: "What is certain is that Paul Pogba never wanted to break a rule."
Testosterone is a hormone that increases the endurance of athletes.
Nado said Pogba had violated rules when prohibited non-endogenous testosterone metabolites - substances not naturally produced by the body from testosterone - were found, and the results were "consistent with the exogenous [external] origin of the target compounds".
According to information put into the public domain by the Football Leaks website, when Pogba re-signed for Manchester United in summer 2016, Pogba's five-year contract was a basic £7.75m each year.
A loyalty bonus of £3.75m a year was also included. If United qualified for the Champions League, Pogba netted a further £1.85m.
In addition, Pogba had a £3m-a-year image rights deal. His agent Mino Raiola, who died in 2022, was paid £41m to help take Pogba back to United.
Juventus then re-signed Pogba on a four-year deal in July 2022 after he ran down his contract at Manchester United and left as a free agent.
Pogba said that he experienced depression after falling out with his manager Jose Mourinho during the Portuguese manager's time in charge at Old Trafford.
In Pogba's first spell at Juventus, from 2012-16, he made 178 appearances across all competitions and won three league titles, scoring 34 goals, before re-joining United for a then-world record transfer fee of £89.3m.
The 2018 World Cup winner's return to Turin has been beset by persistent injury problems, which also led to him missing the 2022 World Cup in Qatar.
Pogba has played a total of 51 minutes as a substitute this season in games against Bologna and Empoli.
Last season he played 108 minutes over six Serie A games, made three appearances and one assist in the Europa League, and managed 11 minutes in the Coppa Italia - a total of 162 minutes and no goals.
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