The 33-year-old announced his retirement from professional football on May 9, 2013, after a successful battle against acute leukaemia.
The Bulgarian, whose illness has been in remission since August 2012, will study for his coaching badges while performing under his new role, and is keen to pass on experience from his 17-year-old playing career.
"I'm very excited by this new challenge and I wish to thank the club and the manager, Paul Lambert, for giving me the opportunity to continue my association with Villa, which I have always regarded as a privilege," he told the club's official website.
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"My hope is that I can assist Gordon through my own experience in the game and that I can help the young lads to progress, become better players and better human beings. There are important values that we have always stood for at the club and we will continue to do so."
Petrov has represented Villa 218 appearances since joining in 2006, earning 107 caps for Bulgaria along the way.
The former midfielder also thanked Wigan fans for their acknowledgement of his retirement during the game on the final day of the season.
He added: "As I have said several times recently, the club has been amazing with me, from the fans to the chairman, Randy Lerner, the chief executive, Paul Faulkner, the manager and the players, as well as staff at Bodymoor and Villa Park.
"Everyone knows that the Villa fans have been magnificent all the way with me and, once more, a big and genuine thank you to you all. But I want to take this opportunity to thank the Wigan fans also.
"I was shocked by how incredible the response was from all of the fans when I walked back on the pitch after Sunday's game. It was a very powerful demonstration of how united football can be.
"Finally, thank you to football fans everywhere because I know how fans of so many clubs in many countries have accepted me into their hearts and stood by me during my illness.
"My gratitude will hopefully be evident from what I intend to put back in the game with all my heart, with all my soul and with all my ability."