Malla Reddy, who represents Malkajgiri Lok Sabha constituency here, joined the TRS in the presence of party president and Chief Minister K Chandrasekhar Rao.
Welcoming Malla Reddy into the party fold, Rao said the entry of the MP into TRS should be seen as part of "reconstruction of Telangana".
TDP won 15 Lok Sabha seats in AP and one (Malla Reddy from Malkajgiri) in Telangana in the 2014 general elections.
Though the party had won 15 Assembly seats in the 2014 elections (simultaneously held with Lok Sabha polls), its strength came down to three as 12 MLAs joined the ruling TRS.
Meanwhile, the Chief Minister also said the annual budget of Telangana would be to the tune of Rs two lakh crore by 2019-20 and up to Rs five lakh crore by 2024.
Such a big budget means a lot can be done for welfare of different sections of society, he said. The Telangana government proposed a Rs 1.30 lakh crore budget for 2016-17.