The 29-year-old departed the Red Devils for a second time upon the expiration of his contract at the start of July and has now ended the long-running speculation surrounding his future.
Pogba was frequently linked with a summer transfer to Real Madrid, but a move did not materialise as the Champions League holders instead opted to sign Aurelien Tchouameni from Monaco.
Reports of Manchester City considering a move for the World Cup winner also went nowhere, and he strongly hinted that a return to Turin was imminent on social media last week.
Now, Juventus have officially completed the signing of Pogba on a free transfer, and he has signed a four-year deal with Massimiliano Allegri's side until the summer of 2026.
A statement on the Juventus website read: "When we say goodbye after an intense adventure shared together, there is always a glimmer of hope that we will see each other again, sooner or later.
"With Paul that is exactly what has happened. In 2016 our paths parted after four incredible years. Years in which a talented young French player went from making his First Team debut when still a teenager to scoring his first goal less than a month after making his bow.
"Years in which we learned to hold our breath in anticipation every time we saw him take aim from outside the box, because we knew how it could, and often did, end - with a roar of joy.
"To be precise, Paul scored 14 times from outside the penalty area in his four Serie A seasons, head to head with Miralem Pjanic at the top of that specific scoring chart. Years in which Pogba emerged as a world-class talent, winning trophy after trophy in the black and white stripes, and coming close to Champions League glory in 2015.
"Then we said goodbye, and in the meantime his talent and power came to the fore when as an integral part of his national side he contributed to France's World Cup 2018 triumph.
"Although we parted ways, we never really forgot about each other, and there is something ancestral in the call that after a thousand adventures eventually leads you back home.
"Paul is back in Turin. He left as a boy and returns as a man and a champion, but there is one thing that has not changed - the desire to write unforgettable pages of club history together once more. Pogba is back and we couldn't be happier."
Pogba will wear the number 10 shirt for Juventus and returns to Serie A six years after Juve sold him to Man United for a then-world record £89m.
Between 2012 and 2016, Pogba registered 34 goals and 40 assists in 178 games for Juventus and won four consecutive Serie A titles alongside two Coppa Italias and three Supercoppa Italiana crowns.
Pogba left Man United for a second time after scoring 39 times and setting up 51 more in 232 outings for the Red Devils, winning the EFL Cup and the Europa League in the 2016-17 season.
The France international has become Juve's second free signing of the summer window after the Bianconeri won the race to sign Angel Di Maria following the Argentine's exit from Paris Saint-Germain.