An excellent collective bowling performance helped Mumbai Indians restrict the home side to 131/6.
The MI batters then came out with an aggressive approach, and a commanding batting effort, led by Amelia Kerr (40* off 24), saw them chase down the target with 29 balls to spare.
Chasing 132, MI were off to a breezy start courtesy of openers Yastika Bhatia and Hayley Matthews. The two took the attacking approach straightaway and played some sensational strokes all around the wicket to add 45 for the opening wicket. They hit seven fours and two sixes between them before Sophie Devine finally provided the breakthrough for the hosts by having Bhatia caught behind for 31(15) in the fourth over.
Matthews and captain Nat Sciver-Brunt, though, kept the runs flowing, but the introduction of Shreyanka Patil brought a wicket as she had Matthews (26 off 21) caught at extra cover. The run flow, however, didn't stop as Amelia Kerr came out with an attacking mindset and hit four fours off her first 12 balls to take MI to 95/2 at the halfway mark.
The in-form Kerr kept finding gaps at will as she added 49(35) with Nat Sciver-Brunt to put MI in the driver's seat. Wareham finally provided the breakthrough as she dismissed the MI captain for 27(25) in the 14th over, but it was too little too late as the visitors cruised to a seven-wicket win with Kerr (40* off 24) finishing it off in style with her trademark cut for four.
Earlier, Mumbai Indians won the toss and elected to field. Nat Sciver-Brunt continued to lead the side in the absence of Harmanpreet Kaur, who was yet to recover from a niggle.
The visitors got off to a fantastic start, picking up three wickets inside the Powerplay. Issy Wong struck early as she got the huge wicket of Smriti Mandhana in the third over as the RCB captain miscued her expansive drive to extra cover. Captain Nat Sciver-Brunt then bounced out S Meghana in the fifth over before Saika Ishaque trapped Sophie Devine LBW in the next over to reduce the home side to 34/3 in the Powerplay.
MI maintained the stranglehold and conceded just seven off the next two overs. The pressure got to Richa Ghosh, who departed looking to up the scoring as she hit one straight to the extra cover, where S Sajana caught it on the second attempt, off Pooja Vastrakar. RCB reached 55/4 at the halfway mark.
Sophie Molineux and Ellyse Perry then steadied the ship a bit with a brisk 29-run stand, but Vastrakar returned to dent RCB again as she cleaned up Molineux in the 13th over. Perry, though, continued to lead the home side's fight with some clever strokes, laced with timing and placement, as she added crucial 52 runs with Georgia Wareham (27 off 20) to propel RCB to 131/6. Perry remained unbeaten on 44 off 38. It was an impressive bowling display from the visitors. MI captain Nat Sciver-Brunt kept rotating her bowlers cleverly and used a total of seven bowlers. The visitors didn't concede a single six in the entire innings.