Tshibola became Villa's third signing of the summer on Sunday.
Tshibola became Villa's third signing of the summer when he penned a four-year deal at Villa Park, following the arrivals of Bournemouth captain Tommy Elphick and Italian goalkeeper Pierluigi Gollini.
Villa are thought to have been tracking the 21-year-old for some time and have now got their man as they look to strengthen their squad in all areas of the pitch ahead of the challenge of facing a Championship season.
Tshibola has become a highly-rated young player thanks to some impressive performances in the centre of the midfield for Reading in what was something of a breakthrough season at the Madejski Stadium last term.
Di Matteo is clearly pleased to add the young talent to his midfield, and highlighted to the Villa website the attributes that the former England under-18 international will bring.
The Italian told said: "I am very happy that Aaron has joined.
"He’s a highly-rated and well-respected young player who will provide us with plenty of energy, courage and determination in the middle of the park.
"I am confident he will be a tremendous addition to our squad for the very important new season - and beyond."
Tshibola will link up at Villa Park with his former Reading coach Steve Clarke, currently serving as Di Matteo's assistant at the relegated club, and will be hoping to impress his new management team in pre-season over the next month.