The singing superstar was smoking up to 25 cigarettes a day before she kicked the habit, reported Contactmusic.
Adele had to cancel shows in 2011 when she lost her voice, and she underwent throat surgery soon after. Doctors warned her career would be over if she did not stop smoking, as the habit was scarring her vocal cords, and she was scared of developing serious health problems.
"If I'd carried on smoking I'd probably have died from a smoking-related illness and I think that's really bad," she said.
The "Hello" singer, who is mother to a son named Angelo, recently revealed that after the surgery, pregnancy also changed her voice.