Just over a year ago, world-class batsman Pietersen was briefly exiled from the national side after being accused of sending derogatory text messages regarding then England captain Andrew Strauss to South Africa players.
But following Strauss's retirement, former skipper Pietersen has been "reintegrated" into the England set-up.
QUICK SINGLE: We're an exciting team: Giles
He is now the one star name left in the squad for the ongoing one-day series against Australia, with England resting regular captain Alastair Cook, batsman Ian Bell and bowlers James Anderson, Stuart Broad and Graeme Swann ahead of their Ashes defence 'Down Under' starting in November.
Former England spinner Giles knows Pietersen well, having been alongside him for much of the South Africa-born shotmaker's maiden Test hundred, a superb 158 against Australia at The Oval that secured a draw which saw the Ashes regained in 2005.
"I've got a decent relationship with Kev, I've played a lot of cricket with him and he's one of the best players in the world," said Giles at Edgbaston, his old Warwickshire home ground, where the third ODI against Australia takes place on Wednesday.
Giles added Pietersen, who averages nearly 50 in Tests and 42 in ODIs, enjoyed the responsibility of being a senior figure in a largely inexperienced squad, having been excused duty from both the shared Twenty20 series with Australia and England's six-wicket ODI win away to Ireland in Malahide.
"Kev gets a bad rap a lot I think for some of the stuff he says and does, but for me in this group he has been great with these young guys," Giles said.
"There is a danger that when a size of personality like him comes back into the group that they are in awe, but he's been fully involved and been great."
In the absence of Cook and Bell, Pietersen found himself opening in the second ODI at Old Trafford on Sunday, where Australia won by 88 runs to go 1-0 up in the five-match series following Friday's washout in Leeds.
Set a daunting 316 for victory, Pietersen could only watch from the other end as England collapsed to 38 for three.
But he still managed 60 at nearly a run-a-ball, including six fours and two sixes, to provide England with a rare highlight during an otherwise largely forgettable display.
Asked if Pietersen preferred opening, Giles insisted he was unconcerned as the decision to install him at the top of the order in Manchester had been his alone and not the batsman's."I didn't really ask him, I just told him he was opening. He clearly enjoys opening, he's got two hundreds and a 60 in his last three innings as an opener."