TDP MLA Rajender Reddy, who announced his loyalty to TRS last week, officially joined the ruling party of Telangana on Tuesday.
"I officially joined TRS in the presence of the Chief Minister. The results of Warangal by-election, GHMC elections and Narayanakhed bypoll has 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.
The Naidu-led outfit had won 15 seats in the 2014 Assembly elections but now holds only five.
Speaking on the rising number of party defectors, Naidu said last week that his party would overcome the crisis. Recalling that TDP had faced several hurdles in its 34-year history, Naidu told an extended meeting of the party's Telangana unit that workers were the real strength of TDP.