A beaming BJP President Rajnath Singh made this announcement at a news conference at his residence after another round of hectic parleys by the leaders of the two parties on seat-sharing in Bihar ahead of the Lok Sabha elections.
Singh said the BJP will contest the remaining 33 seats in Bihar.
"I have complete faith that this alliance between the BJP and the LJP will benefit NDA not only in Bihar but also in other states in the country," he said.
He noted that Paswan was joining the alliance after Dalit leaders Ramdas Athavale and Udit Raj had joined BJP recently.
Singh said Paswan will meet party patriach L K Advani and BJP Prime Ministerial candidate Narendra Modi in the next few days. The LJP supremo will also share the dais with Modi at the latter's rally on March 3 in Muzaffarpur in Bihar.
Paswan exuded confidence that the next government will be formed by the National Democratic Alliance(NDA).
"Next goverment will be a NDA govt," he said.
"You will ask me about Modi. As far as Modi ji is concerned, LJP is now a part of NDA and NDA has already declared Modi as its PM candidate, he added.
Paswan parted ways with BJP by resigning as Coal Minister from the NDA government in April 2002, citing Gujarat riots.