The Tripura Pragatishil Gramin Congress (TPGC), formed in April 2013 by breakaway leaders of the Congress, merged with the Bharatiya Janata Party here.
Bhowmik, a former legislator from the main opposition Congress, formed the TPGC to intensify the campaign against the Left Front government.
Another former Janata Dal member of the Tripura assembly and Congress leader Arun Kanti Bhowmik, a senior lawyer, joined the BJP at a function.
Former Indian Administrative Service officer Bijoy Debbarma also joined the BJP in the same function.
Dasgupta said: "In recent months, thousands of workers and leaders from various political parties have joined the BJP and many more are expected to join in the coming months."
In his speech, BJP leader Ramlalji asked BJP leaders and workers in Tripura to induct more and more people into the party fold.
"If the BJP works properly, we will be able to oust the Left Front from power in 2018," Ramlalji added.
The BJP - for the first time - secured a majority in five gram panchayats and won 141 seats in the three-tier gram panchayat elections in July last year.