With Kalra scoring freely, India won by eight wickets as they chased down Australia's 216 all out with more than 11 overs to spare.
The opener's century included eight fours and three sixes, and he was well supported by wicketkeeper Harvik Desai, who was 47 not out when he finished the match with a boundary.
The pair put on 89 for the third wicket, while Prithvi Shaw scored 29 at the top of the innings and Shubman Gill added 31.
"I really can't express what I'm feeling now," said captain Shaw.
"It was the final, a very crucial hundred from Manjot. Gill was batting really well. And the two pacers, Mavi and Kamlesh, (have) been excellent throughout the tournament."
Man of the match Kalra, not surprisingly, felt the wicket was ideal for batting.
"I enjoyed it a lot. The conditions were good. Not a difficult wicket, it was flat and good to bat on," he said.
Australia's innings, all over in the 48th over, was held together by Jonathan Merlo's 76 after it fell apart despite a promising start.
Jack Edwards (28) and Max Bryant (14) batted at a run a ball through the first five overs.
But once both were dismissed by Ishan Porel, the steam went out of the Australian innings.
Merlo and Param Uppal (34) put on 75 for the fourth wicket but it took more than 17 overs, and there was little resistance from the following batsmen.
Porel finished with two for 30 while left-arm spinner Shiva Singh was instrumental in slowing the Australian run rate with two for 36.
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