Have-a-go Joe is pride of the Lions.
Root (115 not out) and Michael Carberry (72 not out) barely had a moment's worry against a depleted attack as England knocked off 197 to win with more than a session to spare.
Root's share brought him his second first-class hundred and it was easy pickings as he accelerated the scoring rate and the West Indies notably took their feet off the pedal.
The tourists' mid-match fightback faltered immediately on the final morning.
They had defied expectations yesterday, when Kieran Powell and Shivnarine Chanderpaul helped them wipe out a mammoth first-innings deficit.
But the tail lasted barely 30 minutes today and after bowling their opponents out for 390, the Lions moved with the minimum fuss to 61 without loss at lunch.
By contrast, the West Indies cut hapless figures in the field.
Without strike bowler Kemar Roach - who took a blow on his right hand batting against Stuart Meaker this morning to go with the ankle he twisted two days ago - stand-in captain Kirk Edwards' options were further compromised when seamer Ravi Rampaul left the field after four overs with the new ball.
Darren Bravo was required to bowl only his second spell in first-class cricket and Root and Carberry were predictably untroubled when his scurrying medium pace was introduced as first change.
The Lions' openers, who discovered today that team-mate Jonny Bairstow will be the man to replace the injured Ravi Bopara in England's squad for Lord's, turned on the style as the Windies conceded with barely a whimper after lunch.
Rampaul was back on the field at least, but neither he nor Fidel Edwards was used as the tourists opted for apparent damage limitation to their pace-bowling resources and allowed off-spinners Shane Shillingford and Marlon Samuels to go through the motions.
Root passed his 50 with his sixth four when Samuels went round the wicket and induced an edge from the new angle, at catchable height, wide of slip.