Prince William brought a royal flavour to Radio 1's Big Weekend festival in Bangor, when he and girlfriend Kate Middleton joined 20,000 music fans.
The prince met chart-topping London rapper Tinie Tempah, who said: "He was a nice guy. We were just talking and getting familiar."
Florence and the Machine played for nearly an hour to end the first day.
The festival is being welcomed as a boost for the tourist profile of north Wales.
Tempah added of his meeting with the prince: "It was a real big deal for me."
He said: "I was a little bit overwhelmed but it was good. We've never met before. He just said he was, 'feeling everything and a big fan of the music'."
Chart-topper Ellie Goulding also met the prince, and said she was "overwhelmed" after he said he enjoyed her set.
The prince has been learning to fly search-and-rescue helicopters at nearby RAF Valley on Anglesey and is due to take up a posting at Number 22 Squadron if he completes his training successfully.
Earlier in the day, large crowds saw Cheryl Cole and Justin Bieber on the big top main stage, as well as Alicia Keys, Dizzee Rascal and Scouting For Girls.
Acts due on Sunday include Pendulum, Rihanna, JLS, Pixie Lott and Paolo Nutini.
The BBC held a "lottery" for the 40,000 tickets, with many going to people living in the local area.
But local tourism officials have been celebrating a bumper weekend, with the influx of visitors filling up hotels and bed and breakfast.
North Wales Tourism chief executive Esther Roberts said: "Publicity for the event has been great, especially as things have been happening in the area all week."