The jury convicted the 55-year-old on six out of 13 counts after a four-week case in his hometown of Chicago.
He was acquitted of fixing a state trial on child pornography charges in 2008.
Last year the Bump n’ Grind singer was convicted of sex trafficking and racketeering in New York. He was later sentenced to 30 years in jail.
The latest verdict is expected to add years to his incarceration.
The artist, whose real name is Robert Sylvester Kelly, was found guilty on Wednesday of three counts of enticing minors for sex and three counts of producing child sexual imagery.
The jury did not find him guilty of obstructing justice relating to his 2008 trial, which ended in acquittal.
Two of his former associates, who were also accused of fixing the 2008 trial, were on trial with him, but were acquitted of all charges.
The 2008 trial centred on a 30-minute video of Kelly abusing a 14-year-old girl. The victim – known by the pseudonym “Jane” – declined to testify in court 14 years ago and jurors ultimately acquitted him on all counts.
But Jane, now 37 years old, testified last month that she is the person in that footage. She said Kelly had sexually abused her hundreds of times before she turned 18.
That tape and two others were shown to jurors during the trial. Four other women accused the singer of abusing them as children, and more than 30 witnesses testified.
During Monday’s closing arguments – which featured graphic descriptions of child abuse – one juror suffered a panic attack. She was dismissed and replaced with an alternate juror.
Assistant US Attorney Elizabeth Pozolo described how the video shows Kelly urinating on the girl.