According to a report published in India Today, 67-year-old Badar Sayeed was an MLA from Triplicane constituency in Chennai from 2006 to 2011 while the party was in the Opposition.
AAP's media in-charge M Lenin also confirmed reports of Sayeed joining their party, in the presence of convenor Christina Samy.
However, it will be decided weather Sayeed will contest in Lok Sabha elections or not.
Sayeed, who felt 'sidelined' in the AIADMK since the party came to power in Tamil Nadu said that she joined AAP for personal reasons and not due to political reasons. She refused to divulge further details.
Considered as bold and outspoken, Sayeed was Jayalalithaa's schoolmate and was two years senior to her.
She is a renowned lawyer in the Madras High Court, whose action to part ways with AIADMK has left stunned not only the party's insiders but also the political observers.