The 27-year-old singer -- who has a history of drug and alcohol abuse -- checked in to London's The Priory clinic last week and has reportedly been warned by doctors that she won't have long to live if she doesn't dramatically change her lifestyle.
A source said: "It's the last chance saloon for Amy. Doctors have come down hard on her because of the severity of her situation. It's a harsh reality but she had to hear it."
Amy's father Mitch Winehouse and boyfriend Reg Traviss were by her side as she received the daunting news, but insiders insist the singer took the decision to check into rehab herself.
The source added to The Sun newspaper: "They are worried about her. Mitch has been down this road before during Amy's drug addiction. But she is there of her own accord this time and wants to sort herself out."
The 'Back to Black' hitmaker is no stranger to rehab, undergoing stints in the same clinic between 2007 and 2009 to help her addictions to Class A drugs.
As she made her way to the facility last week, she was reportedly seen purchasing a small bottle of vodka and drinking it before she checked herself in.
An onlooker said: "She seemed out of it. She was stumbling about, slurring her words.
"I was shocked to see her buy vodka so early in the day, and even more shocked to see her knock it straight back."