The 36-year-old ended his playing career with the Turin club, with whom he enjoyed a three-year spell between 2009 and 2012, winning the Serie A title with Juve in 2011-12.
Andrea Zanchetta had previously been in the role of youth-team head coach, with Grosso - part of the Italy side that lifted the 2006 FIFA World Cup - serving as his assistant, but he now takes up a different position within the club's backroom staff.
A statement of Juve's website read: "Fabio Grosso has today been confirmed as the new Primavera head coach.
"The World Cup winner replaces Andrea Zanchetta, who will take up another technical role within the club's youth academy."
Grosso also counts spells at Inter, Lyon and Palermo on his resume.
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