Forensic pathologist Dr Lindsey Thomas said "the activities of the law enforcement officers resulted in Mr Floyd's death" from lack of oxygen.
Mr Chauvin, 45, was filmed kneeling on Mr Floyd's neck for more than nine minutes during his arrest last May.
The ex-officer is on trial for murder and has denied the charges against him.
The footage of Mr Chauvin, who is white, with his knee on African-American Mr Floyd's neck sparked global protests against racism.
Prosecutors are trying to prove Mr Chauvin's use of force resulted in Mr Floyd's death, while Mr Chauvin's defence are seeking to show he was following his training and that drugs and heart disease may have caused Mr Floyd's death.
On Friday, the prosecution also called medical examiner Dr Andrew Michael Baker, who performed the post-mortem examination of Mr Floyd.
He said Mr Floyd's death was due to his interaction with law enforcement, but said his drug use and underlying heart disease also played a role.