"We are happy that Balihari Babu, a founder member of BSP along with Kanshi Ram, who built BSP brick and brick has joined the party," All India Congress Committee general secretary Digvijay Singh told mediapersons in New Delhi.
Singh said the former BSP member met Congress President Sonia Gandhi, who approved his admission in the party.
He added that old loyalists of BSP were being sidelined due to the opportunistic politics and policies of UP Chief Minister Mayawati.
"BSP has now become a supermarket in which criminals are preferred," 59-year-old Balihari Babu said in a stinging criticism of Mayawati.
"I am joining Congress as I have full faith in the leadership of Sonia Gandhi, Rahul Gandhi and Digvijay Singh," he said.
The BSP has diverted from the path shown by B R Ambedkar and he was joining the Congress to fulfill the aspirations of the founding father of the Indian constitution, he added.
He was a member of RS and resigned this year.