The 21-year-old featured twice this season under the tutlege of new Everton manager Rafael Benitez.
In his final game for the Merseyside club, Kean was sent off in the Carabao Cup second-round win over Huddersfield.
A statement from Juventus confirming the deal read;
"Homecoming.
"This is the perfect phrase to describe Moise Kean's official return to Juventus from Everton. The 21-year-old returns to the Club, where not only did he take his first steps in professional football, but where he grew up, as a boy and a player, within our youth sector.
"Moise is back and he joins us on loan."
Juventus added: "Now he is back home, and we are ready to welcome him back with great pleasure. Welcome back, Moise."
Juventus have the option to buy for a reported £24 million which includes bonuses of up to £2.5 million.
Kean started his career at Juventus, becoming the club's youngest-ever debutant in 2016.
The pacey forward in last season was on loan at Paris St-Germain as he scored 16 goals in 36 matches.
Kean's arrival somewhat seems as a replacement for departed Cristiano Ronaldo who is keen on returning to Manchester United.
Moise Kean joined Everton in 2019 for a fee in the region of £27 million but failed to cement a place in the starting line-up at Goodison Park.
