The soul-jazz diva shot to fame with her album, "Back to Black." The global hit won five Grammys and made Winehouse - with her black beehive hairdo and old-fashioned sailor tattoos - one of music's most recognizable stars.
Police confirmed that a 27-year-old female was pronounced dead at a home in Camden Square. The cause death was not immediately known. London Ambulance Services said Winehouse had died before the ambulance crews arrived at the scene.
Winehouse's music was often overshadowed by drug use, legal run-ins and constant tabloid coverage of her erratic stage appearances and stints in hospital and rehab clinics. Performances became shambling, stumbling train wrecks, watched around the world on the Internet.
Last month, the singer canceled her entire European summer tour after an embarrassing appearance in Serbia. She was jeered and booed, after she stumbled onto the stage, mumbled through her songs and sometimes wandered off.
She recently went back to rehab to get ready for her tour, spending a week in London's Priory clinic, which offers treatment for psychiatric problems, drug and alcohol addiction.
Though she was often reported to be working on new material, fans got tired of waiting for the much-promised followup to "Back to Black."
Occasional bits of recording saw the light of day. Her rendition of The Zutons' "Valerie" was a highlight of producer Mark Ronson's 2007 album "Version," and she recorded the pop classic "It's My Party" for the 2010 Quincy Jones album "Q: Soul Bossa Nostra."
But other recording projects with Ronson, one of the architects of the success of "Back to Black," came to nothing.
She also had run-ins with the law. In April 2008, Winehouse was cautioned by police for assault after she slapped a man during a raucous night out.
The same year she was investigated by police, although not charged, after a tabloid newspaper published a video that appeared to show her smoking crack cocaine.
In May 2007, Winehouse married music industry hanger-on Blake Fielder-Civil. That November, Fielder-Civil was arrested for an attack on a pub manager in 2006. Winehouse stood by her new husband throughout his trial, but the two divorced in 2009.
Winehouse's health often appeared fragile. In June 2008 and again in April 2010, she was taken to hospital and treated for injuries after fainting and falling at home.
Her father said she had developed the lung disease emphysema from smoking cigarettes and crack, although her spokeswoman later said Winehouse only had "early signs of what could lead to emphysema."
The Associated Press contributed to this report.