"My father-in-law Bhagwat Jha Azad was former Congress Chief Minister (of Bihar). The Congress is like home to me, it's like a mother to me," she said at a press conference today.
She did not rule out the possibility of her husband Kirti Azad, a former cricketer, also following her into the party.
"Only the time will tell, anything can happen, just wait," she said.
Ms Azad joined AAP in November. She was BJP spokesperson and also a key leader of the party's Delhi unit for years until she quit alleging that she had been sidelined.
Kirti Azad, a Lok Sabha member from Bihar, was suspended by the BJP in December 2015 for "anti-party activities" after he went public with allegations of corruption in Delhi's cricket body DDCA when it was headed by Finance Minister Arun Jaitley. Mr Azad was issued a show-cause notice for indiscipline and accused of defying party orders.
Delhi Congress president Ajay Maken said Ms Azad would strengthen the party.
Mr Maken also had good words for her husband as he shared memories of entering the Delhi Assembly as a first-time legislator along with Kirti Azad in 1993.
Two other AAP leaders, including Rajiv Mishra and Sarita Kambojia, also joined the Congress with Ms Azad.
(with inputs from PTI)