And when he was announced as a surprise guest at a White House tea reception honouring military mothers he received a standing ovation and more whoops of delight from US servicewomen and their children.
The seven-day visit is the Prince's first to America since he caused outrage by being photographed naked during a weekend break in Las Vegas last year.
He was a surprise guest whose attendance had been kept secret from the 170 invited mothers, grandmothers and youngsters.
As the Prince walked into the White House's east room Mrs Obama told her guests “Well, surprise” to cheers.
The first lady added: “It is an honour to welcome Prince Harry to the White House today.
“As you all may know, Prince Harry is a captain in the Army Air Corps in the British Armed Forces.”
This reference to Harry's role in the military received a loud cheer from the guests and Mrs Obama went on to highlight his career, saying: “In January he returned from his second deployment to Afghanistan.
“He has spent much of his time supporting our wounded warriors and the families of our fallen. This weekend he will be attending the 4th Annual Warrior Games at Colorado Springs.
“We are absolutely thrilled he could be with us today. He just arrived in DC. He only has a limited time here. But when he heard about this tea and all of you, he wanted to be here to personally thank you for all your service.”
Mrs Obama and Dr Jill Biden, the wife of Vice President Joe Biden, hosted the White House event in honour of military mothers.
It was part of their Joining Forces project, a nationwide initiative launched in 2011 to encourage Americans to support and provide opportunities for the military and their families.
Before Harry was introduced to the military mothers he had joined their children who were making Mother's Day goody bags in the White House's state dining, filling them with bouquets of roses, edible salted dough jewellery and baked crisps.
With Mother's Day traditionally held on the second Sunday of May in America, the children were busy at work.
But the Prince, who is a self confessed big kid at heart, soon joined in bending down to talk to the children and pulling faces and joking with the youngsters.
At one point Mrs Obama joked that the parents were getting “a couple of minutes of free babysitting”.
Earlier in the day hundreds of screaming girls gave Harry a deafening welcome when he arrived at the Russell Senate Office building on Capitol Hill for a photographic exhibition highlighting the work of the Halo Trust.
The Prince barely glanced at them so keen was he to see the exhibition.
He was joined by former presidential candidate Senator John McCain who stepped in as a replacement for his wife Cindy, a leading US anti-landmine campaigner, after she was taken ill.
The royal has followed in the footsteps of his mother Diana, Princess of Wales by supporting the Halo Trust, founded in 1988, and this year the became patron of its 25th anniversary appeal.
Diana famously highlighted the work of the organisation when she was pictured wearing a face mask and protective clothing during a visit to a minefield being cleared by the trust in Angola in 1997.
Harry also visited Africa to promote the charity's work travelling to Mozambique in 2010 where, under supervision, he detonated several mines and met people who had lost limbs to landmines.
Despite Harry's lack of interest in his fans, around 50 girls got close enough to him as he chatted to Mr McCain during the tour of the exhibition.
Happy Carlock 20, an intern from Texas, said the Prince surpassed her expectations: “You could hear hearts breaking all over the room when he left. He is so cute, better than I expected.”
Mr McCain said: “He was kind of embarrassed (by the screaming), I think a normal reaction.
I'm sure it's not the first time he has had that experience, but in all the years I've been coming here I've never seen such an unbalanced gender gap.“
Mr McCain, a former fighter pilot who was held hostage after being shot down in Vietnam, said: “He knew I had been shot down and I told him he was probably a much better pilot than me because he hadn't been shot down.”
The tour will showcase the Prince as a modern, hardworking royal in contrast to last summer's high-profile gaffe when he was photographed nude during a “strip billiards” party in a £5,000-a-night hotel in Las Vegas.
In January when Harry returned from his second deployment to Afghanistan, where he served as an Apache helicopter co-pilot gunner, he admitted he had “let himself and his family down”.
The tour will also take the royal to New York where he will support the Great Campaign, a government initiative which promotes the UK around the world on the back of the success of the Diamond Jubilee and London 2012.
Harry will also attend a baseball event in the Big Apple as he promotes a sports programme involving his Royal Foundation.
On the final day Harry will play in the Sentebale Polo Cup in aid of his Africa-based charity.
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