The idol was found in a bag lying abandoned under a tree by a fisherman at Jayantipur village where the temple is located.
He also informed the family to which it belonged, police said.
The family members rushed to the spot and identified the idol, the police said adding it would be kept in the force's custody till the end of investigations.
The 18th century idol is made of alloy, including gold. It was stolen from Jayantia Kali temple at Jayantipur village on November 8 by miscreants after breaking into it, the police said.