Off-spinner Powar was the wrecker-in-chief in the meagre Karnataka second innings total of 185, chasing 391, with a haul of 5 for 84. It was his third such display this season and added meat to his first innings figures of 4 for 70.
Gangling left-arm spinner Kulkarni, who had taken five wickets in the Karnataka first innings total of 166, gave his younger partner good support with figures of 3 for 53.
Barring skipper Sujit Somasunder's knock of 40 in 120 balls with five fours and a defiant, hard-hitting unbeaten 45 from Sunil Joshi, who was their best bowler too, there was little of note in the Karnataka second innings.
Joshi, in particular, played with ease on the spinning track against a Mumbai attack weakened by the absence of captain and leg-spinner Sairaj Bahutule who could not take the field because of a pulled hamstring.
Earlier, Mumbai declared their second innings at their overnight score of 264 for eight.
Mumbai secured four points and increased their tally to 21 with a match in hand against Delhi while Karnataka went out of contention for a semi-final berth after failing to get a point.
Scores: Mumbai 292 and 264 for 8 decl. Karnataka 166 and 185 (S Somasunder 40, S Joshi not out 45; N Kulkarni 3 for 53, R Powar 5 for 84).