Root was a career-best 133 not out and England captain Eoin Morgan 75 not out, with their unbroken stand worth 143.
London: Joe Root scored an unbeaten century as tournament hosts England beat Bangladesh by eight wickets in the opening match of the 2017 Champions Trophy at the Oval on Thursday.
England, set 306 for victory, finished on 308 for two with 16 balls to spare. Root was a career-best 133 not out and England captain Eoin Morgan 75 not out, with their unbroken stand worth 143.
Opener Alex Hales was out for 95. Earlier, Bangladesh made 305 for six after losing the toss.
Tamim Iqbal top-scored with 128 and put on 166 for the third wicket with Mushfiqur Rahim (79). But when both batsmen were out in successive deliveries from fast bowler Liam Plunkett, the innings faltered. Plunkett led England's attack with four wickets for 59 runs from his maximum 10 overs.
Tamim Iqbal c Buttler b Plunkett 128
Soumya Sarkar c sub (Bairstow) b Stokes 28
Imrul Kayes c Wood b Plunkett 19
Mushfiqur Rahim c Hales b Plunkett 79
Shakib Al Hasan c Stokes b Ball 10
Sabbr Rahman c Roy b Plunkett 24
Mahmudullah not out 6
Mosaddek Hossain not out 2
Extras: (7w, 1b, 1lb) 9
Total: (for 6 wickets) 305
Did not bat: Mashrafe Mortaza, Mustafizur Rahman, Rubel Hossain.
Fall of wickets: 1-56, 2-95, 3-261, 4-261, 5-277, 6-300
Bowling: Chris Woakes 2-1-4-0, Mark Wood 10-1-58-0, Jake Ball 10-1-82-1, Ben Stokes 7-0-42-1, Liam Plunkett 10-0-59-4, Moeen Ali 8-1-40-0, Joe Root 3-0-18-0.
Jason Roy c Mustafizur b Mashrafe 1
Alex Hales c sub (Sunzamul) b Sabbir 95
Joe Root not out 133
Eoin Morgan not out 75
Extras: (2lb, 2w) 4
Total: (for 2 wickets) 308
Did not bat: Ben Stokes, Jos Buttler, Moeen Ali, Chris Woakes, Liam Plunkett, Mark Wood, Jake Ball.
Fall of wickets: 1-6, 2-165
Bowling: Mashrafe Mortaza 10-0-56-1, Shakib Al Hasan 8-0-62-0, Mustafizur Rahman 9-0-51-0, Soumya Sarkar 2-0-13-0, Mosaddek Hossain 7.2-0-47-0, Rubel Hossain 10-0-64-0, Sabbir Rahman 1-0-13-1.
Result: England wins by 8 wickets
Umpires: Sundaram Ravi, India, and Rod Tucker, Australia.
TV umpire: Bruce Oxenford, Australia. Match referee: David Boon, Australia.