62-year-old Satpal Maharaj, an MP from Pauri Garhwal, joined the BJP in the presence of party's president Rajnath Singh at the party headquarters in New Delhi.
He has reportedly promised support of ten MLAs to the BJP.
While addressing the media-persons, Maharaj "lashed out Congress saying it failed to rehabilitate the people affected by last year's floods".
While praising BJP's prime ministerial candidate Narendra Modi, Maharaj said, "Modi is ready to serve country and we should give him the opportunity to make India, a 'superpower' country."
"India will progress under Narendra Modi's leadership", he said.
Maharaj joined Congress in 1989.
Satpal Maharaj has promised support of ten MLAs to the BJP.
Last week, while expressing a deep sense of hurt, Satpal Maharaj had said neither he nor anyone else from his family would contest 2014 Lok Sabha elections and advised the party to field a dedicated party worker from the seat.
"No one from my family would contest the polls. I have already decided not to contest due to neglect of party workers. My suggestion to the party is that it should field some dedicated party worker from Pauri seat," Maharaj had said in a statement.
Accusing party leaders of ignoring his requests, he said he had sent a list of party workers to former chief minister Vijay Bahuguna as well as Harish Rawat demanding that they should be honoured but still nothing has happened.
"This has hurt me," he said.
He said despite his repeated requests to both Bahuguna and Rawat over the past two years for a railway line between Rishikesh and Karnaprayag, land has not been given.
"Similarly, my request seeking a ground in Gauchar for naval officers to camp during recruitment has also been pending for long."
"Those who lost their homes in the natural calamity last year have not got alternative land. Where will they build their homes in a situation like this? All my files, be it the one seeking land for a graveyard or for construction of naval recruitment centre in Ramnagar have all been pending for long.
"Nothing happened despite my requests to both Bahuguna and Rawat over the past two years. All this has hurt me," he said.