But Jemima Phillips, 28, who played at the wedding of the Prince of Wales and the Duchess of Cornwall, was found not guilty of being involved in three burglaries.
The Royal College of Music graduate, of the Forest of Dean, Gloucestershire, had already admitted one count of attempted fraud.
Co-defendant and ex-boyfriend William Davies, 41, of Cheltenham, was found guilty of four counts of burglary after a trial at Gloucester Crown Court.
Judge Michael Harington granted Phillips bail for the preparation of a pre-sentence report.
But he warned: "All sentencing options are open to me on the next occasion - that is to be understood."
Phillips said she would not comment on the case until after she is sentenced on December 22.
But in her candid evidence she confessed she was hooked on heroin even while she held her royal appointment.
She told the jury that her younger brother died at an early age, she was bullied at school and has been in a series of abusive relationships.
The former semi-finalist in BBC's Young Musician Of The Year said her disabled brother, Jerome, died at the age of 13, when she was just 14 herself.
Phillips said her family life was "dysfunctional" and her mother and father had "not shared a bed for a long time" although all still live together at the family home in St Briavels.
She began playing harp at the age of eight, and progressed quickly through the grades, playing concerts and weddings at the age of 14.
In 2004, Phillips said she was "fortunate" to be asked to play for Charles and was later appointed royal harpist in July that year.
She said: "I took over as royal harpist; even then my drug problem had started.
"Sometimes I would just play background music at private functions, when I would be sat a few feet away from the Prince, sometimes it would be concerts."
Phillips held the post until 2007, and in that time played at numerous royal venues and occasions, including the wedding of the Queen's grandson, Peter Phillips, and Autumn Kelly.
She continues to play the instrument at concerts, recitals and as a teacher at local schools, earning up to £2,750 a month.
But her life had been blighted by "disastrous" relationships, her last being with co-defendant Davies.
She told the jury she had two abortions, and started using crack cocaine shortly after the second termination, when she was 23 and living in London.
She met Davies in January this year on a street corner in Gloucester, when he gave her a bag of heroin.
They met regularly and she bought valium from him, to help her fight her habit, and in March they became a couple, she claimed.
She said: "He was romantic and charming. He had a wonderful side to him. But, like Jekyll and Hyde, due to previous girlfriends cheating on him he could get quite jealous."
Later in their relationship, Davies would sneak into their home to stay the night.
It was alleged that both burgled four homes between May 22 and May 28. But Phillips was only convicted of handling and the attempted fraud.
Explained how she agreed to the deception, she said: "When I first met Will he had one of my leaflets - it's got photos of me and Prince Charles. He went round telling his friends and the dealers about me," she said.
"I was getting comments from those people like 'Say hello to Prince Charles for me'. I was worried about those people selling my story to the press, about my drug addiction."
Phillips told the jury she had been clean for two and a half months and was in therapy.
She graduated from the Royal College of Music with both a Bachelors and a Masters degree.
She featured in the first concert to be recorded from the ballroom at Buckingham Palace and gave the first public appearance on the gold Royal Harp at the Llangollen International Festival.
Davies had already admitted five counts of handling but was found guilty today of taking wallets, bank cards, laptops, mobile phones and cash in four burglaries.
It was alleged that Phillips waited outside or acted as driver during the raids in local areas such as Lydney and Coleford.
But the jury cleared her of those allegations and found that Phillips, formerly of Ebbw Vale, Blaenau Gwent, only looked after the items.
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