India recovered from a dire 77-6 to post a decent 161-9 with Suryakumar hitting a scintillating 84 not out off 49 balls.
The US managed 132-8 in reply, putting up a decent fight but never really coming close to chasing down the target.
"Only I can tell how much pressure I was feeling," player of the match Suryakumar said. "But I had the belief. I knew if I bat till the end, I can make a difference."
"It was a little different wicket. But...we cannot brush everything under the carpet. We need to bat much better."
Earlier, the predominantly Indian fans at the Wankhede Stadium probably expected sixes and fours to rain down after U.S. captain Monank Patel elected to field.
Instead, it was a long procession of India's top-order batters returning to the pavilion after a spectacular meltdown of the world's top-ranked T20 team.
Sharma golden duck
Opener Abhishek Sharma, the world's number one T20 batter, fell for a first-ball duck and in the final Powerplay over Shadley van Schalkwyk claimed three wickets in five deliveries to leave India reeling on 46-4.
Ishan Kishan (20) and Tilak Varma (25) could not convert their starts while Shivam Dube departed for a golden duck in that over from van Schalkwyk.
Rinku Singh, Hardik Pandya and Axar Patel also perished trying to swing their way out of trouble.
But Suryakumar responded to the crisis with a captain's knock as he raced to a 36-ball fifty before plundering 21 runs from the final over bowled by Saurabh Netravalkar.
Mohammed Siraj (3-29) vindicated his inclusion in the side with an early two-wicket burst, while Arshdeep Singh also tasted success as they reduced the US to 31-3 in the Powerplay overs.
Sanjay Krishnamurthi (37) and Milind Kumar (34) defied India with a 58-run stand but once the partnership ended, India were firmly in charge.
"I thought our bowlers did a good job," the US captain Patel said.
"We dropped catches and that cost us. At one stage, felt we could restrict them for 130."
In Colombo, the Netherlands nearly pulled off a major upset before Faheem Ashraf's breezy cameo secured Pakistan a nervy three-wicket win with three balls to spare in Group A.
In a group C match in Kolkata, West Indies fast bowler Romario Shepherd claimed four wickets in five balls, including a hat-trick, as the twice champions thumped Scotland by 35 runs.