Speaking at a summit about sustainable tourism in Edinburgh, Scotland, on Wednesday, the host of the event said Harry asked to be called by his first name, as he begins his withdraw from senior royal duties this month.
"He's made it clear that we are all just to call him Harry, so ladies and gentlemen please give a big warm Scottish welcome to Harry,'' host Ayesha Hazarika said while introducing him.
Harry flew commercial from his family's new home in Canada and took a train to reach the conference, where he spoke about the potential environmental impact of increasing global tourism.
In the wake of that criticism, he announced that he had partnered with leading travel companies to create Travalyst, a global initiative aimed at improving conservation and sustainability in the travel industry.
Harry noted in his speech Wednesday that by 2030, there will be 1.8 billion people traveling for vacation.
"This massive increase will mean we see more of the world's beautiful destinations closed or destroyed, more communities becoming overwhelmed,'' he said.
The conference marked the duke's first appearance in the United Kingdom since he and Meghan learned they will no longer be able to use the term "royal" starting in April, when they officially step down from their duties.
For now, their shared Instagram account retains its "Sussex Royal" handle. Harry recently used it to plug an upcoming meeting with rock star Jon Bon Jovi in connection with Harry's Invictus Games for wounded military veterans.
A spokesman for the couple said last week said they will no longer use the Sussex Royal brand name in any territory after spring 2020.
Meanwhile, Meghan remained in Canada with their 9-month-old son, Archie, during Harry's visit to Scotland.
Their final announced engagement as senior royals is scheduled for March 9, when they will join the royal family for the Commonwealth Service at Westminster Abbey.