The judge, Harry D. Leinenweber, handed down the sentence after R. Kelly was found guilty by a jury of child pornography and enticement of a minor.
Kelly is currently serving a federal 30-year jail term for three counts of production of child pornography and three counts of enticement of a minor to engage in criminal sexual activity.
The latest verdict found Kelly guilty of sexually molesting his 14-year-old goddaughter, with concrete video evidence presented by the prosecution during the trial.
Prosecutors labelled the singer a "serial sexual predator" who went to great lengths to conceal his abuse of minors.
The U.S. District Judge sentenced R. Kelly to 20 years imprisonment, with 19 of those years to be served concurrently with his earlier sentence.
This is instead of the 25-year sentence prosecutors had demanded. The remaining year will be served consecutively or after the completion of the earlier sentence.
Throughout the sentencing hearing, the singer refused to speak on his behalf and remained silent for most of the hearing. Kelly has consistently refused to accept responsibility for his crimes.