Derek Chauvin, 45, was filmed kneeling on Mr Floyd's neck for more than nine minutes during his arrest last May.
The widely watched footage sparked worldwide protests against racism and excessive use of force by police.
Chauvin was found guilty on three charges: second-degree murder, third-degree murder and manslaughter.
He will remain in custody until he is sentenced and could spend decades in jail.
The 12-member jury took less than a day to reach their verdict, which followed a highly-charged, three-week trial that left Minneapolis on edge.
