"I officially joined TRS in the presence of the Chief Minister. The results of Warangal by-election, GHMC elections yesterday and Narayanakhed bypoll today showed that we have to work for our Telangana," he told reporters.
People believe that only TRS can ensure development of the State, he said.
Reddy said he also joined TRS in the interest of development of his Assembly constituency - Narayanpet in Mahabubnagar district.
The 10 TDP MLAs in Telangana, who switched loyalty to TRS, last week urged the Assembly Speaker to merge them with the Chandrashekar Rao-led outfit. Meanwhile, TDP has sought the disqualification of four of them.