Dorjey, along with his supporters, were welcomed into the party fold by party general secretary Nizamudin Bhat, a PDP spokesman said.
He said the Dorjey's decision to join the party followed his meeting with PDP leaders from Kargil.
Dorjey said both congress and National Conference had failed to develop Ladakh region and both communities - Muslims and Buddhists - were exploited by the two parties for their "petty political interests".
He said most of the good decisions about development of Ladakh including empowerment of Hill Development Councils were taken by Chief Minister Mufti Mohammad Sayeed in the past.
Bhat said Dorjey's entry into the PDP will further expand party's base in the hill regions of Kargil and Leh.
This will also help to strengthen communal harmony in the region, he said.