Mr Rao's resignation comes ahead of Arvind Kejriwal's visit to Davangere in Karnataka on March 4.
In a setback to the Aam Aadmi Party in Karnataka, its prominent face and former Bengaluru police commissioner Bhaskar Rao on Wednesday quit the party and joined the ruling BJP in the state.
Mr Rao had joined the AAP just 11 months ago in New Delhi in the presence of the AAP supremo and Delhi Chief Minister Arvind Kejriwal.
After joining the BJP in the presence of BJP state chief Nalin Kumar Kateel today, the retired IPS officer said only BJP can strengthen India and bring back the lost glory.
"We all should join hands to strengthen Prime Minister Narendra Modi who is striving to make 'Ek Bharat, Samruddh Bharat' (One India, Prosperous India). I am also impressed by the prominence given to youth and women in the BJP," Mr Rao told reporters here.
He also said he will seek the guidance of Mr Kateel, Chief Minister Basavaraj Bommai, former CM B S Yediyurappa, and other senior BJP leaders.
Mr Rao's resignation comes ahead of Arvind Kejriwal's visit to Davangere in Karnataka on March 4.
Speaking on the occasion, Mr Kateel said Mr Rao has accepted the ideology and philosophy of the BJP after gaining one year of political experience in the AAP.
He added that the retired IPS officer is impressed by the functioning of the party under the leadership of Modi at national level and Chief Minister Bommai at state level.
(Except for the headline, this story has not been edited by NDTV staff and is published from a syndicated feed.)