Mumbai, resuming at their overnight score of 300 for seven, added another 50 runs before being all out off 109.3 overs in 511 minutes.
Needing 186 runs to make the defending champions bat again, the visitors were bundled out for a paltry 94 off 50 overs to give the hosts their third outright win this season.
Ajay Kudua was the top scorer for Kerala with 22 off 29 balls with four hits to the fence while C M Deepak (20 off 85 balls with two fours), left hander Sreekumar Nair (19 off 39 balls with tow fours) and Sujith Somasunder (16 off 89 balls with two fours) were the others to reach double figures.
Earlier, in the morning session, Vinod Kambli recorded his second century of the season when he made 102 off 145 balls with ten hits to the fence in 232 minutes before being trapped leg before the wicket by Prashant Chandran.
Wicketkeeper Vinayak Samant scored 21 off 23 balls with four fours while Kerala medium pacer Chandran took seven for 71.
For Mumbai, right arm medium pacer Usman Malvi (two for 18) gave good support to Powar and Patel in routing Kerala.
In the first innings, the three bowlers were instrumental in restricting Kerala to 165 all out.
Kambli, Muzumdar seize initiative