Morgan will lead out an England side at Headingley on Friday missing regular captain Alastair Cook, Ian Bell, James Anderson, Stuart Broad and Graeme Swann, with all those players rested following the Ashes.
But Pietersen will take his place in a relatively inexperienced team, and Morgan is happy to have the Surrey batsman on board.
"Kev offers a hell of a lot as a senior player and as a batsman," he said.
"As a senior player he leads by example with the confidence in which he goes about his business.
"People rub off on that and that's crucial.
"When I first came into the team, he was one of the more senior players and he was a guy you could turn to and ask difficult questions or have no hesitation in turning to him for a positive option.
"In that regard I think he's fantastic to have in the squad and back in for the one-day series."
With Cook and Bell both missing, Pietersen may be given the chance to open the batting for England, a role he has filled before in the 50-over game.
But Morgan insists he is not the only candidate at the top of the order, and said: "It's certainly an option. Kev's opened the batting for England before and done well.
"He also bats in the middle order as a very explosive player. He's very versatile in that regard, so we'll be looking at both options.
"They're [the openers] filling big shoes. Cooky and Belly have been very successful now for a couple of years and they've been a huge part of our success as a one-day team
"With the two new balls in one-day cricket, it makes that role more difficult now."
While Morgan and Pietersen will be expected to fill leadership roles within the group, the Middlesex man is excited to see young players coming through and could hand a new cap to Sussex bowler Chris Jordan on Friday.
"Those games [as captain] in particular I've really enjoyed," he said.
"The things I've most enjoyed about them has been handing out caps to debutants.
"It's fantastic to see guys being rewarded for a lot of hard work over a number of years, and being rewarded by pulling the England shirt on, and that makes me smile every day.
"We've got a young, talented, exciting team playing in this series and it can be a stepping stone looking ahead to the 2015 World Cup. We want to win that World Cup and that's a huge goal of ours."
Australia have dropped batsman David Warner for the series and fast bowler Mitchell Starc has been ruled out with a sore back.
However, despite back problems of his own, captain Michael Clarke said he gave no thought to resting himself ahead of the Ashes.
"It was a no-brainer for me if I wanted to stay here and play the one-dayers," Clarke said. "I want to play every game I can for Australia.
"I'll prepare today, as I have done over the past few days, like I would if it was the first test of the Ashes. It's just as important to me.
"I think it's important I'm here with the team and performing and leading from the front."
CLARKE FANCIES AUSTRALIA's CHANCES
Michael Clarke has warned England that Australia will be a tougher proposition ahead in the first of five one-day internationals.
Clarke’s team slumped to a dismal 3-0 defeat in the recent Ashes series and is out for some revenge.
The Australian batsman is convinced his team's high one-day international ranking, which contrasts sharply with their lowly Test placing, is an accurate reflection of their ability to dominant in the limited overs format.
"I think we're ranked second in one-day cricket and in Test matches we are fifth so there's a big difference," Clarke said.
"We've got a lot of young players coming through our one-day system but in both forms of the game, we haven't been as consistent as we would like.
"I think in patches we've played really well, and generally at home in our conditions pretty well.
"But we need to perform when we're away from home, and our most recent trips to the UK have not been successful. Let's hope we can turn that around."
A one-day international series victory would ease any perceived pressure on Clarke's captaincy before they have to face England on home soil in the Ashes rematch at the end of November.
But he insists he is just focused on finishing the tour of England on a high note.
"When you're captain, you're accountable - especially when you're not performing well and your team is losing," Clarke said.
"I understand that. But me wanting to win this series has nothing to do with my captaincy.
"It's about this team, where we're at and trying to move forward and improve in the one-day format and get back to being number one in the world.
"That's why it's important we win this series
“I want to see this one-day team get back to where it belongs, at the top of the tree."
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