Indulging in a spot of style recycling, the Duchess of Cambridge turned heads in a printed silk Whistles dress, which she first wore during the Diamond Jubilee celebrations earlier this year.
Arriving at the Stratford stadium, Kate Middleton chatted to Prime Minister David Cameron and London 2012 chairman, Seb Coe, before taking her seat.
And while Kate did have Prince Harry for company, poor old Prince William was stuck on search and rescue duty in Anglesey.
Nevertheless, Kate Middleton and Prince Harry still seemed to have a whale of the time at the ceremony, enjoying prime seats to watch the Spice Girls, Jessie J and Madness - among many other acts - perform.
Prince Harry's appearance on behalf of the Queen - who was also absent from the ceremony - is said to be part of a move to leave the Olympics in the hands of younger members of the royal family as they up their official commitments.
Prince Harry, Prince William and Kate Middleton were all official London 2012 Olympics ambassadors, while Prince Harry was introduced, using his full name, Prince Henry, at the start of last night's ceremony as the official representative of the Queen.
He said of the London 2012 Olympic Games: 'They will stay in the hearts and minds of people all over the world for a very long time to come.
‘I congratulate all the athletes who have competed. They have shown us that there are few boundaries to human endeavour.’
Kate Middleton and Prince Harry have made several Olympic outings together in William's absence, enjoying a bonding session as they met Team GB athletes at the Olympic park last week.
They've also been spotted sharing a joke at the equestrian arena, and generally seem to get on like a house on fire.
What were your thoughts on Kate Middleton and Prince Harry's closing ceremony appearance? Let us know in the comments box below…