The singer, who has sold almost 20 million albums, was diagnosed by a specialist one year ago. She described the knowledge as "a relief" when speaking ahead of the release of her seasonal charity single, O Come All Ye Faithful, a "duet" with Elvis Presley taken from her latest album, Home For Christmas.
"Asperger's doesn't define me," Boyle said. "It's a condition that I have to live with and work through, but I feel more relaxed about myself. People will have a greater understanding of who I am and why I do the things I do."
Boyle, from Blackburn, West Lothian, admitted that she is "not strong on my own" but added: "When I have the support of people around me, I am fine."
Referring to the popular belief that she has learning difficulties, Boyle said: "I have always known that I have had an unfair label put upon me."
Asperger's is a form of autism that means sufferers struggle with their emotions and have difficulty in social situations, often unable to pick up on non-verbal cues.
Boyle has had difficulty singing live because of anxiety, which she now believes is a result of her condition.
Robert MacBean, policy and campaigns officer for the National Autistic Society (NAS) Scotland, said: "Huge strides have been taken in changing attitudes towards autism and increasing understanding of the lifelong, disabling condition that touches the lives of over 58,000 people in Scotland.
"But there is still a tendency to think of autism as a condition that just affects children. By revealing her diagnosis, Susan Boyle is helping to highlight that there are older people with autism who need our support and care."
On Friday, Boyle makes her acting debut in the film The Christmas Candle, to which she contributed an original song, Miracle Hymn.
And on Wednesday, she is the subject of an STV documentary about her Scottish summer tour and a US concert in front of 20,000 people.