Thomas Lane is already serving a two-and-a-half-year federal sentence for violating Mr Floyd’s civil rights.
Prosecutors and Lane’s lawyers had agreed to a recommended sentence of three years — which is below the sentencing guidelines — and prosecutors agreed to allow him to serve that penalty at the same time as his federal sentence.
Judge Peter Cahill accepted the plea agreement, saying he would sentence Lane below the guidelines because he had accepted responsibility.
He said in his sentencing: “I think it was a very wise decision for you to accept responsibility and move on with your life”.
Under Minnesota rules, it is presumed Lane would serve two years of his state sentence in prison, and the rest on parole.
Mr Floyd, 46, died in May 2020 after Officer Derek Chauvin pinned him to the ground with a knee on his neck as the black man repeatedly said he could not breathe.
Lane, who is white, held down Mr Floyd's legs.
J Alexander Kueng knelt on Mr Floyd’s back, and Tou Thao kept bystanders from intervening during the nine-and-a-half-minute restraint.
The killing, captured on widely viewed bystander video, sparked protests in Minneapolis and around the globe as part of a reckoning over racial injustice.
Wednesday’s sentencing hearing was held remotely. Lane appeared via video from the Federal Correctional Institution Englewood, the low-security federal prison camp in Littleton, Colorado.
Chauvin was convicted of murder and manslaughter and was given a twenty-two-and-a-half-year state sentence in 2021. He also pleaded guilty to a federal count of violating Mr Floyd’s civil rights, and his state and federal sentences are being served at the same time.
Kueng and Thao were also convicted on federal civil rights charges and were sentenced to three and three-and-a-half years respectively.
They have not yet reported to federal prison, and are scheduled to go to trial on state charges of aiding and abetting both murder and manslaughter in October.
When Lane pleaded guilty to aiding and abetting second-degree manslaughter earlier this year, he admitted that he intentionally helped restrain Mr Floyd in a way that created an unreasonable risk and caused his death.
As part of the plea agreement, a more serious count of aiding and abetting second-degree unintentional murder was dismissed.
In his plea agreement, Lane admitted that he knew from his training that restraining Mr Floyd in that way created a serious risk of death, and that he heard Mr Floyd say he could not breathe, knew Mr Floyd fell silent, had no pulse and appeared to have lost consciousness.
The plea agreement says Lane knew Mr Floyd should have been rolled onto his side — and evidence shows he asked twice if that should be done — but he continued to assist in the restraint despite the risk.
Lane agreed the restraint was “unreasonable under the circumstances and constituted an unlawful use of force”.