Out for revenge over Bangladesh for India's five-wicket defeat in the 2007 World Cup which helped lead to their first stage exit, Sehwag hit his highest one-day score off 140 balls, leading India to 370-4.
Chasing the improbable target of scoring nearly seven-and-half runs an over, Bangladesh ended their 50 overs on 283-9, which is still their highest total in a World Cup match in their fourth tournament.
Tamim Iqbal and Shakib Al Hasan made 70 and 55 runs respectively but after they departed Bangladesh were unable to even approach the formidable and ever increasing asking rate.
Pace bowler Munaf Patel gave India's depleted pace attack, which suffered a blow ahead of the game with Ashish Nehra missing out following reports of a back injury, a boost by claiming four wickets for 48 runs in the win.
Man-of-the-match Sehwag, blasting his second ever World Cup century, made Bangladesh skipper Shakib bitterly regret his decision to bowl first on a placid wicket with 14 fours and five sixes.
He added 203 runs with Virat Kohli for the third wicket with the latter also completing a century in the final over. He finished on 100 not out off 83 balls in his World Cup debut.
"I've always said this is a revenge game and we really played well," a beaming man-of-the-match Sehwag said during the presentation ceremony while delirious Indian fans blew conch horns around the stands.
"I started really well and kept telling myself I have to bat at least 20, 30 overs. If I could bat (that long), I could maybe score a hundred in 30 overs." Sehwag needed a runner after reaching three figures having hurt his left knee while trying to push Rubel Hossain for a single in the 38th over of India's innings.
"It's a little sore," he said.
"We bowled too many bad balls and that cost us the game. Virender Sehwag played a really good innings and he took the game away from us," summed Shakib up simply.
India 370-4 in 50 overs (Virender Sehwag 175, Virat Kohli 100 not out; Mahmudullah 1-49) def. Bangladesh 283-9 in 50 overs (Tamim Iqbal 70, Shakib Al Hasan 55; Munaf Patel 4-48).
