The catcher announced his retirement on March 1 after 15 seasons with the team following a trade from the Seattle Mariners.
"Jason was one of the most respected players of his era and will be a key voice as we move forward," general manager Ben Cherington said Thursday. "He will be involved in a number of areas including major league personnel decisions, evaluations, and mentorship and instruction of young players."
At Wednesday night's home finale, Varitek was among players honored as members of the "All Fenway Park Team" during a pregame ceremony that capped a year of celebrations for the ballpark's 100th anniversary. He was named the second-string catcher behind Carlton Fisk.
Varitek served as Red Sox captain from Dec. 24, 2004, until his retirement.