England captain Nat Sciver-Brunt is the history-maker, smashing exactly 100 not out off 57 balls to achieve the landmark in the competition's fourth season and 82nd match overall.
The veteran, who helped Hobart Hurricanes win the WBBL last month, hit 16 fours and a six as she helped Mumbai Indians pile up 4-199 in Vadodara.
Royal Challengers Bengaluru were never really in the chase with both Grace Harris and Georgia Voll out cheaply as five wickets fell for 15 runs. While an explosive late flurry from Richa Ghosh (90 off 49) worried Indians RCB ultimately fell 15 runs short at 9-184.
Mumbai's win ensured the defending champions remain in contention for this year's play-offs while league leaders RCB, who have now lost successive matches having begun with five wins, continue to wait to confirm their place in the final.
Nine players had previously reached the nineties, topped by Voll who was left stranded on 99 not out in Lucknow last March.
Voll is one of six Australians to reach the nineties, being joined by Alyssa Healy (96 no), Beth Mooney (96 no), Meg Lanning (92), Tahlia McGrath (90 no) and Ellyse Perry (90 no).
New Zealander Sophie Devine has scored 99 and 95 while India's Smriti Mandhana (96 no) and Harmanpreet Kaur (95) make up the nine, with Ghosh now joining them.
Voll was in the field watching as Sciver-Brunt found herself at the non-striker's end on 99 as the last over began. A scrambled single off the second ball got her to the danger end, and she clubbed a single through mid-off two balls later to bring up her hundred.
"I'd seen a few players get out inthe nineties so I didn't want to replicate that, but also wanted to get as many runs for the team," said the 33-year-old.
"It's my first T20 hundred but hopefully not the last."
RCB's bowling had become increasingly ragged with only Sciver-Brunt's in-form England colleague Lauren Bell, with 2-21 off four overs, avoiding the onslaught.
It was Bell who removed Hayley Matthews for a 39-ball 56, cleverly bowling her behind her legs to end the 131-run 77-ball second-wicket partnership that set Mumbai's innings up.
RCB needed something special from one of their Australians, both of whom are capable of big innings but have dipped in form.
Harris had hit 28 in four innings since her blistering 85 in RCB's second match, but looked in good touch as she raced to 15 off eight before a thin underedge to the keeper off Shabnim Ismail sent her packing.
Voll replaced her, coming in after scores of 54 no, one and 11 so far this WPL. She was nearly bowled first ball, then clothed a fortuitous four off her second. A much sweeter boundary followed but then the Queenslander nicked a wayward legside ball to be caught behind for nine.
With Mandhana having perished to Matthews earlier in the over that left RCB 3-31, which was quickly 5-35 as Ismail bowled Gautami Naik then caught Radha Yadav.
There was no way back from there, especially after key batter Nadine de Klerk (28) was caught by, inevitably, Sciver-Brunt.
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