Sporting, who led 2-0 at half time, scored through Ogba Kalu (13th), Deepak Devrani (31st) and Karpeh (71st).
The win takes Sporting Clube de Goa to 10 points from five matches, the same as Salgaocar FC and Pune FC. Rangdjied United remained at the bottom with two points from six matches.
Sporting coach Oscar Bruzon, looking for a hat-trick of wins, made only one change in his side, which beat Mohun Bagan, by bringing in Deepak Devrani in place of Joyner Lourenco.
Sporting started on an attacking note and had an early chance to surge ahead when Jovel Martins' cross from the left had Boima Karpeh in a good position to head the ball, but the striker sent it wide from the edge of the six yards.
Rangdajied goalkeeper Surjay Kumar Pariyar came to his side's rescue twice as he denied another header by Karpeh and Ogba Kalu's shot off the rebound with Martins once being the provider.