Put into bat, Mumbai rode on an aggressive 81 by South African Quinton De Kock to post an imposing 187/5, but Buttler's 43-ball knock studded with eight fours and seven sixes set the tone before Royals survived a scare to finish the game in 19.3 overs.
The match was a forgettable one for young West Indies pacer Alzarri Joseph (0/53 in 3 overs), who was hammered for eight fours and three sixes and then was injured trying to save a boundary. Buttler smashed him for two sixes and four fours to bring down the equation to a manageable run-a-ball.
Buttler first conjured a 60-run opening stand with skipper Ajinkya Rahane (37) to lay the foundation and then added 87 runs for the second wicket with Sanju Samson (31).
Buttler initially played second fiddle to Rahane but then upped his ante once skipper was gone. The Englishman in the eighth over; hit Rahul Chahar for a six, and then in next over, smashed two sixes off Krunal Pandya as he raced to 50 off 29 balls.
When Buttler departed in the 14th over, Rajasthan needed 41 runs. But then came the twist in the tale when Mumbai did make a comeback of sorts sending four batsmen—Samson, Rahul Tripathi (1), Steve Smith (12 ) and Liam Livingstone (1)—back to the pavilion as Rajasthan slumped to 174.6 from 147/2.
However, Shreyas Gopal (13 not out) and K Gowtham (0 not out) held their nerves to take the side home in a tense situation. Gopal hit the winning boundary off Hardik Pandya as celebrations erupted in the Rajasthan camp.
Earlier, Quinton de Kock hit a belligerent 81 as he powered Mumbai Indians to an imposing 187 for 5 against Rajasthan Royals in their Indian Premier League game here Saturday. A late cameo from Hardik Pandya (28 off 11 balls), in which smashed three sixes and one four ensured Mumbai neared the 190-run mark.
Rohit and De Kock took the opposition attack to the cleaners as the two added 96 for the first wicket. They started the onslaught in the third over amassing 18 runs with the South African hitting a six and four off Krishnappa Gowtham.
And then Rajasthan made a good comeback removing Surya Kumar Yadav (16) and Kieron Pollard (6) to reduce the hosts to 136/3.
Rajasthan bowlers made a splendid comeback as they removed De Kock and Ishan Kishan before the Hardik show.