Boyle, a dowdy-looking 47-year-old woman, first was met with rolling eyes and snickers when she went on stage and earnestly declared her ambition to be a famous singer.
The snide reactions quickly turned to shocked expressions from the judges and thunderous applause from the audience, however, as she began her breathtaking rendition of "I Dreamed a Dream" from the musical "Les Miserables." Infamously sharp-tongued judge Simon Cowell beamed at Boyle during her performance and told her afterward that it was "extraordinary."
The BBC said Boyle's "Talent" appearance has already gotten more than 5 million hits on YouTube.
"I entered the competition because I wanted to have a chance at my singing," the British broadcaster quoted Boyle as saying. "I found it very nerve-wracking to begin with, but once I settled down and began to sing, I thought that the audience accepted me a bit more. Then I sort of relaxed and began to enjoy it."
Boyle, who is currently unemployed, said she began singing in choirs and school concerts when she was 12.
The BBC said U.S. actress Demi Moore and her husband, actor Ashton Kutcher, are already fans of Boyle, with Moore posting a message on YouTube that said: "It made me teary! ... This just made my night."