This disqualifies him from Parliament and renders him ineligible for contesting elections for at least six years.
The RJD President was taken to jail after being convicted by a special CBI court here in the fodder scam case.
65-year-old Prasad was taken to the Birsa Munda Central Jail here.
The court has fixed October 3 for pronouncement of sentence against Yadav, former Bihar chief minister Jagannath Mishra and others convicted in the case.
The RJD chief faces immediate disqualification as Lok Sabha member under a recent Supreme Court order that an MP or MLA would stand disqualified immediately if convicted by a court for crimes with punishment of two years or more and under some other laws even without jail sentence.
While coming out from the court, Yadav appeared calm and did not take any question as his car sped away to the jail located at Hotwar on the outskirts of Ranchi, adjacent to the National Games Village.
Besides Prasad, the court of Pravas Kumar Singh convicted another 44 accused, including Mishra, six politicians and four IAS officers, for fraudulent withdrawal of Rs 37.7 crore from Chaibasa treasury.
Later, the court sentenced IAS officer K Armugam, former Bihar AHD and Labour Minister Vidya Sagar Nishad and former MLA Dhruv Bhagat and five fodder suppliers for up to three years.
Earlier, Prasad, who arrived in the court by a white Ambassador car, appeared relaxed and waved to his party supporters. He sat in the second row in the courtroom as the judge began reading out the judgement against him.