Kelly was charged with allegedly videotaping himself having sex with an underage girl some time between 1998 and 2000. Kelly's attorneys maintained the female on the tape wasn't his goddaughter as prosecutors had claimed. The defense also argued the man on the tape wasn't Kelly.
The 41-year-old recording artist could have faced up to 15 years in prison if he had been convicted.
The jury of nine men and three women got the case Thursday and deliberated for seven and a half hours before announcing its not guilty verdict Friday afternoon, the Chicago Tribune reported.
"R. Kelly was found not guilty because they had the best jury that Cook County could produce," the Tribune quoted Adam as saying. "Two things happened today. R. Kelly got his name back and (his goddaughter) never had to lose hers."
Kelly declined to comment on the outcome of the trial, but did acknowledge his fans, who had gathered outside the court, with a salute and a wave.