The star, who shot to fame after appearing on Britain's Got Talent in 2009, had spent years believing she suffered slight brain damage at birth.
In an interview with The Observer newspaper she told of her relief at finally getting a "clearer understanding" of her condition.
But she vowed: "It will not make any difference to my life."
Asperger's is a form of autism which typically means people with the condition struggle with their emotions and have difficulty in social situations, often unable to pick up on non-verbal cues.
Boyle, 52, revealed she was misdiagnosed after complications at birth.
She said: "It was the wrong diagnosis when I was a kid.
"I was told I had brain damage. I always knew it was an unfair label. Now I have a clearer understanding of what's wrong and I feel relieved and a bit more relaxed about myself."
The singer has gone on to become one of the best-selling British female artists and recently had a cameo role in the festive film The Christmas Candle.
Last year a musical based on her life toured cities in the UK and Republic of Ireland and she has also said a film about her rise to fame is being planned.
Boyle said of her recently diagnosed condition: "It will not make any difference to my life. It's just a condition that I have to live with and work through.
"I think people will treat me better because they will have a much greater understanding of who I am and why I do the things I do."
Scottish singer Susan Boyle has revealed she has been diagnosed with Asperger's Syndrome.