Leroy will primarily be working with Sunderland's Professional Development Phase (PDP) players, supporting their development both on and off the pitch.
The 40-year-old, who made 82 appearances for Boro between 2009 and 2011, began his playing career in Chelsea’s youth system before going on to make more than 300 appearances across the Premier League and Football League.
He had notable spells with Bristol City and Reading as well as spending time with Boro and won nine caps for England Under-21s.
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Since hanging up his boots, Lita has gained valuable coaching experience with the academies of Walsall and Aston Villa. His appointment at Sunderland marks his first full-time coaching position.
Sunderland academy manager, Robin Nicholls, said: “It is great to welcome Leroy to the club. Along with some coaching experience in academy football, he brings with him some fantastic experiences from his highly-successful playing career. I have no doubt that our players will benefit from his knowledge of the game.”