"When the BBC approached me, it just felt right for me to be a part of an institution like Eurovision. I'm excited and raring to go and want the nation to get behind me," Humperdinck, 75, told Sky News.
His hits include "Release Me" and "The Last Waltz." The song he is going to sing in the 57th edition of the competition is being written by Sacha Skarbek, who collaborated with James Blunt on the hit "You're Beautiful," and Grammy Award-winning producer Martin Terefe, Sky News said.
The United Kingdom last won in 1997 with Katrina and the Waves performing "Love Shine a Light."
"Not since the 70s have we had such an established international musical legend represent the nation. We couldn't be more delighted," said Katie Taylor, the BBC's head of entertainment and events. "Engelbert's experience leaves us in no doubt that he will be able to deliver a standout performance in front of 120 million viewers worldwide."