Former Telangana health minister Eatala Rajender joined the BJP on Monday in the presence of Union minister Dharmendra Pradhan.
Mr Rajender has already resigned as the Huzurabad MLA and has also relinquished his membership of the Telangana Rashtra Samithi (TRS).
Welcoming him into the party, Mr Pradhan said the BJP would form the government in Telangana after the next assembly elections.
Mr Rajender was a senior leader of the TRS and has held top portfolios such as finance and health in the K Chandrashekar Rao-led successive TRS governments in the state.
He was removed from the Cabinet over accusations related to land-grabbing.