The soul singer was taken to a Florida court by a woman called Miriam Lee.
She claimed that McKnight was the father of her 14-year-old son after an alleged affair with the musician.
The 'Back At One' star was ordered to give $340,000 (£220,000) in paternity payments as he didn't file court papers addressing the lawsuit. A judge was forced to make a default ruling in Lee's favour.
However, a DNA check has shown that McKnight is not the child's dad. According to TMZ, a judge has dismissed the case.