Spring gala season tends to draw celebrated artists and fashion icons to star-studded black-tie fundraisers around New York City. With a guest list boasting Lionel Richie and Anna Wintour, The King's Trust Global Gala looked no different Wednesday evening.

But one distinguished guest — even if his fleeting stop consisted of a three-and-a-half-minute speech — brought a buzz that had some members of high society lining up along velvet ropes and craning their necks inside Christie's New York auction house. That would be King Charles III , who made his first appearance in the five-year history of the event supporting his nonprofit that helps young people find work.

The buzz was evident from the red carpet.…