Di Matteo returns to Chelsea as coach
Italian Di Matteo played for the Londoners between 1996 and 2002 when injury forced his retirement at the age of 31.
Villas-Boas has also recruited Jose Mario Rocha, a 48-year-old fitness expert who worked alongside the Portuguese at his previous clubs Porto and Academica, the club said on their website.
Another new face is Daniel Sousa who will become head opposition scout, the role occupied by Villas-Boas in his first spell at the club under Jose Mourinho between 2004 and 2007.
Sousa worked alongside Villas-Boas at his two former clubs. Steve Holland, Chelsea's reserve coach last season, will also step up to work with the senior squad.
Di Matteo scored FA Cup final goals in 1997 and 2000, the first of which set a Wembley record for the earliest in a final after just 43 seconds.
The former Italy international was previously manager of Milton Keynes Dons and West Bromwich Albion, the club he left in February.