The prince and his fiancee visited community station Reprezent FM, which provides media training and experience to young people.
Onlookers cheered as the couple arrived at the station, housed inside shipping containers in the diverse south London district, a hub for Britain’s African and Caribbean communities.
Station founder Shane Carey said news of the visit had caused “massive excitement.”
Prince Harry and his brother Prince William support youth projects through their charitable foundation.
Tuesday’s visit was the couple’s second official visit since the couple announced their engagement in November. The U.S. actress and the queen’s grandson are due to marry May 19 at Windsor Castle.