The father-of-three, 41, spoke to American pop stars OneRepublic backstage at the bash after they opened proceedings at The Theatre at Mediacorp.
"I can’t thank you enough," Prince William said. "You were amazing. What a way to start the show. That was incredible."
OneRepublic performed their hits Counting Stars and I Ain't Worried, while British band Bastille and English singer-songwriter Freya Ridings closed the ceremony.
The Prince told Bastille that their performance of Pompeii – about the disaster that befell the Roman city when Mount Vesuvius erupted in 79AD – to close the show profoundly affected those around him in the audience.
"You guys blew it away. Honestly, it was incredibly moving, it was very powerful and I didn't want it to stop. And everyone in front of me was crying. I mean I didn't see behind me but there were tears everywhere. It was so powerful and a great way to finish the show. So thank you so much."
See the Prince's arrival on the green carpet at the awards ceremony.
William is on a four-day solo visit to Singapore in support of his Earthshot Prize, which he first launched in 2020.
LISTEN: What winning Prince William's Earthshot Prize is really like
During a speech at the United for Wildlife Global Summit on Monday, William addressed his wife Kate's absence.
"I'm delighted to be back in Singapore," said William, who last visited the south-east Asian country in 2012 on an official Diamond Jubilee tour with Kate.
"It has been 11 years since Catherine and I enjoyed a memorable visit here on behalf of my late grandmother in her Diamond Jubilee Year."
He added: "And I should mention that Catherine is very sorry she can't be here… she is helping George through his first set of major exams," prompting a series of laughs from the crowd.