Kaul, who was the PDP's Chief national spokesperson, joined the NC in the presence of party president Farooq Abdullah and other senior leaders, a statement from the party said here.
Considered a close associate of PDP founder and former Chief Minister Mufti Mohammad Sayeed, he resigned from the PDP in April last year.
"Kaul resigned from the PDP following the party's unholy alliance with the BJP. He was welcomed in the party fold by Abdullah in the presence of provincial presidents Nasir Aslam Wani and Devender Singh Rana and State Spokesperson Junaid Azim Mattu," the statement said.
Kaul assured that he would continue to strive to serve the people of the State in upholding their political rights, dignity and honour keeping in mind the true aspirations of the people of the state and the principles of Kashmiriyat.