The singer was taken to court for not honouring his engagements at a Las Vegas casino in 2000.
The seven members of the jury unanimously found Stewart guilty of breaking his contract with the Rio Hotel and Casino.
The 60 year-old star was unable to perform at a New Year’s Eve concert because he was still recovering from throat surgery. However, the performer had taken and kept an advance from the Hotel for that show.
Lawyers for Stewart have already announced that they are planning an appeal.