Devinder Singh Sehrawat accused the party of "ignoring" and "cornering" him.
Aam Aadmi Party (AAP) legislator Devinder Singh Sehrawat joined the BJP on Monday, the second legislator to quit the party and join the saffron fold in less than a week.
AAP's Gandhi Nagar MLA Anil Bajpai quit the party and joined the BJP on Friday last week.
Mr Sehrawat, the party's legislator from Bijwasan, joined the party at a press conference in the presence of senior Delhi BJP leaders.
Accusing the party of "ignoring" and "cornering" him, Mr Sehrawat said he was not even invited for party functions.