Medium-pacer Balwinder Sandhu (3-35) bagged three of the six wickets that fell on the fifth and final day at the DRIEMS Ground to bundle out Delhi for 236 runs.
Chasing 440 for a win, Delhi started on their overnight score of 110 for four but found little resistance from the experienced batting line-up that faltered once again.
Rajat Bhatia top-scored with 49 runs with lower-order batsmen Pradeep Sangwan (26 not out) and Parvinder Awana (24) also contributing with useful knocks.
Thakur, who bagged his sixth first-class five wicket haul in the first innings, picked up three wickets in the second innings to flatten Delhi's chance of any win.
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Medium-pacer Wilkin Mota (2-55) and left-arm spinner Harmeet Singh (2-55) also bagged two wickets each to make their presence felt.
On the batting front, Mumbai opener Akhil Herwadkar (161), who struck his maiden first-class century in his team's second innings, was instrumental in taking the Aditya Tare-led side to 450 in the second coming after they were skittled out for 156 when they were put into bat.
Sehwag was run out on 49 in the first innings as Delhi were bundled out for 166, while Gambhir managed 34 in the second innings only to be trapped lbw off Thakur.
Brief Scores:
Mumbai 156 and 450
Delhi 166 and 236 in 87 overs (Rajat Bhatia 49; Shardul Thakur 3-59, Balwinder Sandhu 3-35).