Chasing an imposing target of 530 and staring defeat in the face last evening at 177 for 8, Vidarbha collapsed for 191 by adding 14 runs while losing their last two wickets to medium pacer Shardul Thakur, who ended up with innings figures of 4 for 48 on the fourth and final day of the lop-sided clash.
Thakur, who grabbed 3 for 40 in the first innings, polished off the Vidarbha innings in a morning spell of 2.4-0-2-2 for impressive match figures of 7 for 88.
Mumbai took their overall points tally to 19 from 4 games, three more than second-placed Punjab and five ahead of third-placed Gujarat, who have also played four games each.
The 40-time champions next face another weak team, Jharkhand, at home from December 6-9.
Brief scores: Mumbai 261 and 381 for 4 decl beat Vidarbha 113 and 191 (S Shrivastava 69, S Wagh not out 41; S Thakur 4 for 48, V Dabholkar 2 for 33) by 338 runs.