Mr Prabhakar had been among the founding members of the All Jharkhand Students Union (AJSU)
BJP's principal spokesman Praveen Prabhakar on Sunday resigned from party's primary membership and joined Meghalaya Chief Minister Conrad Sangama-led Nationalist People's Party.
Associated with the BJP for the past five years, Mr Prabhakar had been among the founding members of the All Jharkhand Students Union (AJSU), which fought the 2014 Assembly election in alliance with the BJP, but is contesting separately this time.
He was said to be unhappy with the ticket distribution in the state by the party.
Mr Prabhakar told IANS that he had learnt a lot from Prime Minister Narendra Modi and BJP chief and Home Minister Amit Shah but in Jharkhand, the BJP needed to do some introspection.
He joined the National People's Party, headed by Meghalaya Chief Minister Conrad K Sangma, at its national convention at the Constitution Club on Sunday, and was named its candidate from Nala, which will go to polls in the last of the five phases on December 20.
Shillong MP and former Union Minister Agatha Sangma, Meghalaya Home Minister James Sangma and NPP's Jharkand chief Raj Kumar Poddar were also present at the programme.
The NPP was recently recognised as a national political party by the Election Commission, making it one of the eight to enjoy this status.
Speaking on the occasion, Conrad Sangma recalled his father and former Lok Sabha Speaker PA Sangma had set up the party in 2013, and his dream was that it not remained confined to the northeast but spread to other states across India as a national party to help the deprived.
Hailing Mr Prabhakar's inclusion in his party, Mr Sangma said that he would help the NPP increase its footprint in Jharkhand and other states and thus "all would together help achieve the late Sangma's dream".
Mr Prabhakar said that he does not have any personal grievance with the BJP but it needs to do some soul-searching in his state.
Praising the leadership of PM Modi and Amit Shah, he said that under them, "the nation was progressing on all fronts, but in Jharkhand, the aspirations of the people were being constantly snuffed. I dedicated all I had for the creation of Jharkhand (as a separate state) and will continue to fight all my life for its development. I have full faith that I will get the assistance and guidance of NPP leaders in this endeavour".