Singh was contesting against BJP-led NDA candidate Upendra Kushwaha, who leads the Rashtriya Lok Morcha.
"You are contesting the Lok Sabha elections against the official candidate of the NDA. This act of yours is against the party and has tarnished the party's image and violated party discipline," Bihar BJP told Singh in a letter as quoted by NDTV.
Singh was earlier fielded by the BJP from West Bengal's Asansol Lok Sabha constituency against veteran actor and TMC's bet, Shatrughan Sinha.
However, Singh, whose controversial songs drew sharp responses from the TMC, withdrew his candidature citing personal reasons causing embarrassment for the BJP.
Karakat will go to polls in the seventh and final phase of Lok Sabha elections on June 1.