He told reporters that he would join the BJP on Wednesday. He was in the saffron party earlier as well and had been elected to the Lok Sabha on its ticket.
"Congress is still in the past, unaware of the future. Today, the country is with PM Modi and if the country is with him, I am with him. I will join BJP tomorrow. I have resigned from the party, as well as my membership of Rajya Sabha. Congress is unapproachable and unreachable. I have taken this decision after watching this for a long time," he said.
"Congress is rudderless, direction less and there is a distance from the people... I am supporting Modi because of 'sabka sath sabka vikas'," he added.
Sinh wields considerable influence in the Amethi of Uttar Pradesh and the BJP hopes that his presence will help it consolidate itself in the region, which also includes Raebareli, the Lok Sabha seat of Congress leader Sonia Gandhi.
He had unsuccessfully contested the recent Lok Sabha election from Sultanpur against BJP's Maneka Gandhi.
Sinh's wife Ameeta Sinh, who is the chairperson of the All India Professional Congress in UP, has also quit the Congress.
"Dialogue and communication are the basis of any political party. There is just no scope for any dialogue in Congress. Then there is zero leadership. There is no clarity, nothing can be decided. Over months there is a buzz over whether the Congress president will be a young man or an old man... all these things affected my decision," he said.
The BJP may field him for the Rajya Sabha poll in the coming weeks.
His term was set to end in April, 2020. Rajya Sabha Deputy Chairman Harivansh announced in the House that his resignation has been accepted.
The BJP has recently won over a number of Rajya Sabha members from other parties in its bid to bolster its strength in the House where the ruling NDA led by it does not have a majority.