The French midfielder tested positive for testosterone - a hormone that increases athletes' endurance - after Juventus' first game of the season against Udinese back in August, and has now suffered the heavy consequences.
Pogba was an unused substitute in that game but he later made two appearances off the bench against Bologna and Empoli before he was handed a provisional suspension.
Pogba's positive doping test was also confirmed in a counter-analysis on a second sample in October.
His lawyers claimed that their client had accidentally taken the substance and rejected a plea deal in an attempt to get a lighter sentence, but the prosecution didn't accept their defence.
Pogba has since released a statement on his official Instagram page, declaring he was "shocked and heartbroken" by the news.
"I am sad, shocked and heartbroken that everything I have built in my professional playing career has been taken away from me," 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.
"As a consequence of the decision announced today I will appeal this before the Court of Arbitration for Sport.
"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," Pogba added.
Juventus did not comment but a source confirmed that the club had been notified about the decision of a four-year ban and would assess the next steps.
Pogba, who is still under contract at Juve, will not be allowed to return until 2028, at which point he will be 34 years old.
It has been a torrid second spell for the midfielder at the Italian giants due to injuries following his departure from Manchester United on a free transfer in 2022.
The 2018 World Cup winner barely played last season after knee and hamstring problems as well as knee surgery, which prevented him from playing for France at the World Cup in Qatar.
The Frenchman was among the sport's highest-earning players at his peak after he completed a then-world record transfer of over 100 million euros ($108.42 million) in 2016 to United.
According to a source, Juve are currently paying Pogba a minimum wage of 2,000 euros ($2,169.80) per month.