The `Back to Black` hitmaker - who is planning to release her highly-anticipated third album in January 2011 - performed a surprise charity show at London`s Hawley Arms to 100 fans, who had no idea she would be taking to the stage.
DJ Izzy Lawrence put on the `Apocalypstick` night to raise money for the Nordoff Robbins Music Therapy Charity, but the 27-year-old singer surprised attendees by borrowing a guitar and performing her hit `Tears Dry On Their Own`, as well as tracks from her new album.
Amy - who has previously struggled with drink and drug addictions -only had one alcoholic drink all night, and dismissed her usual late-night lifestyle by heading home at 12.30am.
She told the crowd: "I`m putting on weight you know. It was even a struggle to get into these jeans, I don`t know how I`m going to get them off again."
However, the controversial star proved she is still a wild child at heart, telling unsigned bands who were also performing at the event not to let anyone hold them back.
According to the Daily Mirror, Amy said: "Don`t let anyone tell you you`re wrong and you can`t do it. Keep going. You can make it. Everyone tried to hold me back, but look at me, I`m back."
The star`s last album - her breakthrough, `Back to Black`- was released in 2006.