The parties formally announced the merger at a media meet here.
"Our party OJM has merged with Samata Kranti Dal as it is working for the betterment of labourers, farmers and unemployed youths," OJM president Jagneswar told reporters.
Stating that Mohapatra had always pressed for the need of a strong alliance at the regional level, he said the decision was taken to fulfil wishes of the late leader.
Samata Kranti Dal along with OJM would emerge as a strong regional party as both are working for the uplift of the people of Odisha, said Samata Kranti Dal chief B K Tripathy.
Both Pyarimohan Mohapatra and Braja Kishore Tripathy formed the OJM and Samata Kranti Dal respectively after they had been expelled by the ruling BJD headed by Naveen Patnaik.