The Ranchi lad, who clubbed a rollicking double century three days back, was at his brutal best as he clobbered a whirlwind 102 from 44 balls.
The India One-day gloveman paid scant respect to Bengal bowlers carting them all over the park to make short work of the target of 241.
He clouted 13 boundaries and seven sixes.
Shambazar overhauled Kalighat's score, reaching 242 for four in just 31.4 overs.
Earlier, Kalighat were restricted to 240 losing all their wickets in 47 overs.
Manoj Tewari was the main run-maker with a solid 83. He was well supported by Safi Ahmed who made 42.
Sanjib Sanyal and Md. Ziauddin also chipped in with handy knocks of 32 each respectively.
India discard Shib Shankar Paul was best of the Shambazar bowlers finishing with 3 for 41.
Shambazar will await the winners of the second semi-final between CAB President's XI and Sporting Union, to be held at the Eden on Friday.
The final is slated for Sunday.
Brief Scores:Kalighat: 240 all out (47 overs). Shambazar: 242/4 (31.4 overs).