Put in to bat, India racked up 9-209 after Ishan Kishan (61) and Hardik Pandya (52) struck rapid half-centuries.
They returned to bundle out Namibia for 116 in 18.2 overs to register their second successive victory and top the group because of a superior run-rate to Pakistan, who also have four points from two games.
The Asian arch-rivals will clash in a blockbuster in Colombo on Sunday.
"I think it was a pretty good game for everyone," India captain Suryakumar Yadav said.
"It was not an easy wicket to bat on. The way Ishan and Sanju (Samson) started, it didn't really look like it, but it was a difficult wicket."
With Abhishek Sharma, currently the top-ranked T20 batsman, still recovering from a stomach infection, an out-of-form Samson had another opportunity to impress after India were put into bat on Thursday.
Samson (22) looked keen to make it count too. The right-hander smacked three sixes but frittered away the start and fell in the second over.
But Kishan smashed JJ Smit for four sixes in a row to race to a 20-ball fifty.
India needed 4.3 overs to reach 50, and their next 50 came off 14 balls.
Namibia captain Gerhard Erasmus (4-20) ended Kishan's 24-ball blitz and they managed to apply the brake after the departures of Varma (19) and Suryakumar (12).
Pandya, who hit four sixes, and Shivam Dube (23) provided the late flourish to take India past the 200-mark.
Steenkamp (29) and Jan Frylinck (22) began positively but Namibia kept losing wickets to drift out of contention.
For India, a fit-again Jasprit Bumrah bowled four tidy overs claiming the wicket of Ruben Trumpelmann with a trademark yorker.
Varun Chakravarthy (3-7) was the pick of the Indian bowlers, while fellow spinner Axar Patel and player-of-the-match Pandya claimed two wickets apiece.
"After the powerplay, we thought dew might make bowling tough and we had a chance. But that spell from Varun broke the back of our chase," Erasmus said.
