Root will be replacing Joe Denly, who currently occupies the number three position in the batting order after it was reported the England skipper approached coach Trevor Bayliss with this proposition.
The 28-year-old has made no secret about his preference to bat at number four but he is willing to move up one slot and bolster the Ashes hosts' often fragile top-order that lacks experience.
England recently completed a comprehensive 143-run win over Ireland but not before they were beset by quality bowling in the first innings and collapsed to a paltry total of 85 on the opening day of the Lord's Test.
The team management has thus been persistent in trying to convince Root to come out to bat early in the innings rather than wait for a couple of batsmen to fall to the moving new ball.
Root's averages are not too dissimilar batting at the two positions as he fares 48 at number four while the metric slightly dips down to a shade over 40 at number three.
With plenty of experience under his belt, Root is expected to steer his team's struggling top-order as the present trio upfront has played only eight matches between them.
Denly confirmed the change in his batting position while talking to reporters at Edgbaston.
"Joe Root will bat at three and I'll be batting at four," he said.
"He rang me the other day and told me he wanted to bat three and for me to go in at four. I think Rooty just wanted to get involved in the game, get up there and get out in the middle."
"I'm very excited. I wasn't too fussed where I'd be batting, it's just great to be in the eleven. I've batted at four before for Kent and throughout my career, so it really wasn't a big issue," he added. "I'm just happy to be playing."