The Bulgarian, who last played for Villa four years ago and has since battled and beaten leukaemia, has been invited to take part in the sessions at Bodymoor Heath by new manager Roberto Di Matteo.
Petrov smiled as he arrived at the club's training ground, chatting with Callum Robinson on his way into the facility, ahead of his return to a first-team environment.
The 36-year-old has been training with Villa's Under 21s after declaring his intentions in April to play for his old club once again. He has said that turning out for the senior side has become 'a priority'.
Petrov's last appearance came in March 2012 but he is targeting a new contract if he can prove his fitness.
He is training three times a day and tests earlier this year revealed his fitness levels are close to how he was performing before his enforced retirement.
Di Matteo will pay attention to Petrov during pre-season and the prospect of him playing a friendly on a tour of Austria has not been ruled out.
Petrov joined from Celtic in 2006, signed by Martin O'Neill, and went on to make 186 league appearances. He was inducted to the Villa Hall of Fame three years ago.
New signing Tommy Elphick was also present as Villa started preparations for life in the Championship following their relegation from the Premier League at the end of last term.
The former Bournemouth captain was Di Matteo's first signing, arriving from for a fee in the region of £3million last week.
By Sam Morshead