Gopal (5/35) also registered his best bowling figures, while skipper R Vinay Kumar scalped four for 70 to bowl out ROI for 183 runs in their second innings in 57.5 overs at the Chinnaswamy Stadium.
Gopal picked up three wickets in three balls in the 58th over to bring down curtains to ROI's dismal batting performance in the second innings.
Karnataka skipper Vinay Kumar's four wickets in the second innings also helped him to end with an impressive match figures of 11 for 82.
Resuming their second innings at 114 for three, ROI's middle and lower middle order fell like pack of cards, riding on Gopal and Vinay Kumar's effective bowling as their last seven wickets could add just 69 runs.