Roy is one of the key players for England and his batting so far against Bangladesh has been sensational.
Tournament favourites England, whose rise to the top of the one-day worldwide rankings since Bangladesh knocked them out of the 2015 World Cup has been based on aggressive batting, lived up to his words.
Roy - who dropped a crucial catch and made just eight in England's 14-run defeat to Pakistan at Trent Bridge on Monday - now holds the second-best score by an England batsman at a World Cup, behind only Andrew Strauss' 158 against India in Bengaluru eight years ago.
England were sent in to bat by Bangladesh captain Mashrafe Mortaza on a green-tinged pitch, but Roy and Jonny Bairstow (51) seized the initiative, sharing a first-wicket stand of 128.
Shakib Al Hasan hit a valiant century in the second innings but a lack of significant contributions from other batsmen meant Bangladesh were bundled out for 280 in reply.
Earlier, England were off to a flying start as Roy and Bairstow scored 67 in the first powerplay and then brought up the hundred in 15 overs.
Nevertheless, Roy and Bairstow's half-centuries helped England cross the hundred-run mark easily. In the 35th over, Roy plundered three successive sixes off Mehidy Hasan to complete his 150 in 120 balls but he was holed out by Mortaza at extra cover in the next ball.
At the same time, Bangladesh had won its first match against South Africa.
Buttler raced to a 33-ball fifty but his hip issue left him hobbling and he flicked Saifuddin to the fielder at deep square leg one delivery after smashing a six, his partnership with Morgan having reached 95.
The round-robin group stage sees Bangladesh next play Sri Lanka at Bristol on Tuesday, with England facing the West Indies at the Oval on Friday.
The England batsman was on 96 when he pulled the ball through midwicket and found the boundary courtesy of an error from a Bangladesh fielder.
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