The legislators had announced their decision to support the TRS government earlier this month.
T Srinivas Yadav, MLA from Sanath Nagar in Hyderabad, T Krishna Reddy, MLA from Maheswaram in neighbouring Ranga Reddy district, besides the MLC, Gangadhar Goud joined the TRS in the presence of its president and Telangana Chief Minister K Chandrasekhar Rao.
The development is viewed as a setback to TDP in Telangana.