Chauvin, who is white, was sentenced to 22-1/2 years in prison last year after his conviction on charges of murdering Floyd, a Black man suspected of passing a counterfeit bill.
By entering the plea on Wednesday, now-former officer Thomas Lane avoided an upcoming trial on the more serious charge of aiding and abetting second-degree murder. He agreed to a sentence of three years in prison, the Minneapolis Star Tribune reported. A sentencing hearing has yet to be scheduled.
The two other former officers involved in George Floyd's arrest, Tou Thao and J. Alexander Kueng, are scheduled to face trial in June on both of state charges, according to online Hennepin County Court records.
"His acknowledgment he did something wrong is an important step toward healing the wounds of the Floyd family, our community and the nation," Minnesota Attorney General Keith Ellison said in a statement.
In February, Lane, Thao and Kueng were convicted on federal charges of depriving Floyd of his civil rights by failing to give aid to him when he showed signs of distress while pinned under Chauvin's knee for more than nine minutes.
Chauvin has pleaded guilty in federal court to charges he violated Floyd's civil rights.
Floyd's killing sparked protests in cities around the world against police brutality and racism.