Dharmani, who top-scored in the visitors' meagre first innings tally of 126 with a stubborn 32, was once again the batting hero as he held the lower order together with aplomb to remain unconquered with a superb 86 after a five-hour stay.
But for his valiant knock, that included 8 fours and a six and came off 237 balls, Punjab's hopes of shocking the reigning champions of the last two years would never have materialised.
Fittingly, it was the Punjab wicketkeeper who hit the winning runs in the first over after lunch on the fourth and penultimate day of the semi-final at the Wankhede Stadium.
He struck a four off Avishkar Salvi and then cut the Mumbai medium pacer for a single to point to signal wild celebrations in the Punjab camp who had to wait anxiously till after lunch to see their endeavor fulfilled.
Punjab were poised for a win when the day commenced. Needing 68 more runs for a win after commencing the day at 226 for four chasing 294, they lost three more wickets against a determined Mumbai team who made the visitors earn every run.
Dharmani saw three of his teammates depart and then found an able ally in Gagandeep Singh (15 not out in 65 minutes) to take Punjab home from 261 for 7 to 294 without further loss.
Punjab would meet Railways in the five-day final at Mohali from March 30.
Though Punjab held the upper hand in the morning when they were within sight of entering the national cricket championship's summit clash after a gap of nine years, Mumbai forced them to fight their way.
The 36-time champions' tried every trick in the book to prevent Punjab, who last made the final in the 1994-95 season, from entering the title clash for only the fourth time.
But Dharmani, in particular, stood rocklike to defeat Mumbai's efforts. He eschewed the risk factor totally against the spinners and did not play a false shot barring a streaky one over the slip cordon when Punjab were within handshaking distance of the target.
It was his calm attitude that won Punjab the day even as the visitors lost the wickets of overnight unbeaten batsman Gaurav Gupta, who failed to add any run this morning to his last evening score of 34, Amit Uniyal and Navdeep Singh.
Dharmani, not out 67 overnight, never seemed in a hurry, as he knew time was not a factor. It needed his stay at the wicket right through to ensure victory and he did it in style.
In the morning Avishkar Salvi accounted for Gupta's wicket though the batsman was not at all happy to be declared out caught down the leg side by Mumbai stumper Vinayak Samant. He stood his ground glaring at umpire Subramaniyan before reluctantly leaving the crease.
Punjab, 244 for five at Gupta's departure, lost Uniyal three runs later to Ajit Agarkar. Then Navdeep Singh too left at 261 when he was trapped leg before by Nilesh Kulkarni.
Mumbai, in a final act of desperation, summoned the new ball at 279 for seven after 96 overs, but Dharmani and Gagandeep stood resolutely and saw the 1992-93 champions home.