The singer wore an American-flag-themed stage costume while performing 'Firework', 'Teenage Dream' and 'Part of Me' as part of her set.
The concert - which was hosted by America's First Lady Michelle Obama - took place in Washington and was a celebration for youths ahead of Barack Obama's inauguration later today (January 21).
Usher also performed at the event, while Jimmy Fallon, The Wanted and Ellen DeGeneres formed a montage of celebrity video messages.
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The cast of Glee were also present, with actress Amber Riley giving a rendition of Christina Aguilera's hit ballad 'Beautiful'.
President Obama and Vice President Joe Biden walked out on stage at the end of the show to praise the efforts of the military services and their families.
Beyoncé, Kelly Clarkson and James Taylor are among the performers for President Obama's inauguration today, which marks the leader's second term in office.
