The fun-loving prince – who split from girlfriend of two years Cressida Bonas last week – was attending a special bash to mark the 10th birthday of the charity he co-founded.
Harry, 29, showed off the trace of a tan following his weekend in the U.S. attending the wedding of close friend Guy Pelly and heiress Lizzie Wilson.
Arriving at London's Dorchester Hotel shortly before 7:45 p.m. and wearing a crisp, open-necked white shirt and blue suit, Harry was there to celebrate the important anniversary of the charity that he started with friend Prince Seeiso of Lesotho to aid disadvantaged youngsters in the African mountain kingdom.
Sentebale, meaning Forget-Me-Not, was set up in memory of their late mothers.
Entertaining guests at the Summer Party was singer Joss Stone, while Harry was also set to make a brief speech to introduce the first of several awards recognizing those key individuals and organizations that have supported the charity over the past decade.