Punjab Congress leader and former state finance minister Manpreet Singh Badal joined the BJP here on Wednesday.
Badal joined the party at the BJP headquarters in the presence of various leaders, including Union Minister Piyush Goyal.
Earlier in his resignation letter to Congress leader Rahul Gandhi, Badal said he was "disillusioned" by the party.
"I devoted every ounce of energy to every office I have had the honour of holding, both in the party and the government. I thank you for having provided me these opportunities and for the kindness and courtesy you have shown me in the past," he said in the letter which he posted on his Twitter handle.
"Regretfully, given the prevalent culture within the party and the defiant desire in the present course, I no longer wish to be a part of the Indian National Congress," he said.
Badal, who served as the finance minister in the previous Congress government, said, "Seven years ago, I merged the People's Party of Punjab with your party. I did so with immense hope and an expectation of being integrated into an organisation with a rich history that would allow me to serve both the people of Punjab and its interests to the best of my ability."
"Initial enthusiasm gradually gave way to disappointing disillusionment," he added.