BJP state president Mangal Pandey said that Sunil Kumar and Renu Kushwaha have joined the party and RJD MLA Braj Kishore Singh has joined the party.
"All three of them have resigned from their respective parties and joined the BJP," Pandey said.
Last week four rebel JD-U MLAs, suspended from the party for six years, joined the saffron party.
They were Gayanendra Singh Gayanu, Rajeshwar Raj, Dinesh Kushwaha and Suresh Chanchal. Singh was considered close to Bihar Chief Minister Nitish Kumar before he revolted against him last year.The JD-U had suspended them for involvement in "anti-party activities"
According to BJP leaders, some more JD-U legislators are expected to join the BJP ahead of the assembly polls scheduled for later this year.