The decision was taken today after a marathon three-day meeting of the Dera's 15-member political wing, after which the decision was made to extend support to the BJP, two members of the wing, Kastoor and Rakesh said.
The party has also decided to extend support to the BJP in Maharashtra.
"We will extend support to the BJP candidates in Haryana on all the 90 assembly seats. We have considerable following pan-India and we have also decided to extend support to the BJP in Maharashtra," Kastoor said.
Kastoor, however, maintained that Dera Sacha Sauda head Gurmeet Ram Rahim Singh was not involved in the decision on extending support and the final decision had been taken "collectively" by the political wing.
Notably, Prime Minister Narendra Modi had addressed an election rally at Sirsa, considered the stronghold of the Chautalas, on Saturday.
BJP is contesting all the seats on its own for the first time in the state. In the past, it has played second fiddle to parties like the INLD, Haryana Vikas Party which later merged with Congress, and even with Haryana Janhit Congress before separating from it recently.