Ronaldo will seek to continue Juventus' streak of seven successive Scudetto triumphs in Serie A.
BBC Sport reported in early July that Real were considering an £88 million bid Juve had submitted for the player, who arrived in Madrid from Manchester United for a then-world record £80 million in 2009.
Ronaldo's position at the Estadio Santiago Bernabeu had come into question after he suggested his time at the club was ending following their Champions League final win over Liverpool in May. As mentioned by BBC Sport, strained relations with president Florentino Perez are believed to have in part fueled his decision.
Julen Lopetegui has taken over from the departed Zinedine Zidane as manager, and Ronaldo's exit signals a dramatic shift at the club and the beginning of a new era.
At 33 years of age, Ronaldo's time at the top of the game could be limited, but his impact in recent years has increased rather than diminished with age. He has played a major role in the club's four UEFA Champions League wins in the past five years and won the European Championship with Portugal in 2016.
Ronaldo has also clinched two La Liga trophies at Real, as well as three FIFA Club World Cups, two Copas del Rey, two UEFA Super Cups and two Spanish Super Cups.
It was once thought that if Ronaldo were ever to leave Real, it would be for a return to Old Trafford, but instead, he heads to Juventus, who Real eliminated from the Champions League last season in the quarter-finals with a last-minute Ronaldo penalty.
Ronaldo was also part of the team that beat the Bianconeri in the 2017 Champions League final, but he'll now look to take Juve—runners-up in two of the past four seasons—to continental glory.