Dhawan struck nine fours and a six in his 55-ball unbeaten 73 as the home side chased down the small target of 130 with two overs to spare at Rajiv Gandhi International Stadium at Uppal here.
The India opener, who had an impressive Test debut against Australia in March, shared 74 runs from 9.2 overs with Hanuma Vihari (25 off 23 balls) for the third wicket as the Sunrisers reached 130 for three in 18 overs. Captain Kumar Sangakkara contributed run-a-ball 21.
Dhawan had scored an unbeaten 63 in his first match of the IPL season for a lost cause against Chennai Super Kings in Sunrisers' away match on April 25.
Despite today's win, their sixth in 10 matches, the Sunrisers remained at fifth place with 12 points. Mumbai, whose three-game winning streak was snapped today, also remained at fourth place with 12 points from 10 matches.
Chasing the modest target of 130, the Sunrisers lost opener Akshath Reddy (7) in the third over with just 16 on the board.
Reddy was done in by a Mitchell Johnson slower ball as he attempted to slice it over the covers but ended up ballooning in the air for Dwayne Smith to take an easy catch at covers.
Despite the early jolt, the home side had nothing much to worry about as the asking rate was small and captain Sangakkara and Dhawan finding the boundaries.
Sangakkara hit the first four of his innings off his Sri Lankan compatriot Lasith Malinga in the fifth over and then finished off-spinner Harbhajan Singh with two consecutive boundaries in the sixth over.
Dhawan was also settling down well with a four off Pragyan Ojha and a six off Harbhajan after hitting two boundaries off Dhawal Kulkarni early on.
Dhawan struck two sweetly-times fours off the West Indian while Vihari also found the gap for another boundary.
Visiting captain Rohit Sharma shuffled his bowlers in a bid to break the partnership of Dhawan and Vihari which Mumbai could do only in the 18th over with the latter falling to Kulkarni.
But by that time, it was too late for Mumbai as the Sunrisers needed just three runs to win the match.
For Mumbai, Harbhajan, Johnson and Kulkarni bagged a wicket each.
Earlier, a fine bowling performance from Sunrisers saw them restrict a star-studded Mumbai Indians side to a modest 129 for four.
Pacer Ishant Sharma (2/15) and leggie Amit Mishra (2/24) proved to be the most miserly in their four-over spells.
The others too bowled economical spells with Karan Sharma and Dale Steyn conceding just 25 and 27 runs in their quota of four overs.
Mumbai's Ambati Rayadu played a useful 34-run knock while big-hitter Kieren Pollard (14 of 19 balls) found the going tough on a slow wicket at Rajiv Gandhi International Stadium.
The duo shared an unbeaten 50-run stand for the fifth wicket to take their side past 120. .