He also made Prajapati the coordinator of a programme to celebrate the party's silver jubilee on November 4.
"SP has ensured honour to poor, women and backward after struggle. It is the miracle of SP policies that people from a common family became minister," he said.
Pointing at Prajapati, who was sitting near him, Yadav said "persons like Prajapati have become ministers. He is an undisputed leader and devoted for the party and work for it".
Announcing that SP will be organising a programme on the silver jubilee of the party on November 4 at Janeshwar Mishra Park in the state capital, he said Prajapati will be its coordinator.
He directed all the party MP, MLAs, ministers and workers to participate in the programme.
Chief Minister Akhilesh Yadav had sacked Prajapati, who was the Mining minister, following charges of illegal mining against him. The Allahabad High Court had ordered a CBI probe into it.
He was later reinstated, following intervention of SP chief, and given Transport ministry.