Jason Dalton's surprise move came more than three years after the shootings, which occurred over the course of a few hours in and around Kalamazoo, Michigan.
Jason Dalton, 48, pleaded guilty to all counts of murder and attempted murder and faces a mandatory sentence of life in prison without the possibility of parole.
When asked by the presiding judge whether he was pleading guilty "voluntarily of your own free will", Dalton replied: "Yes".
KALAMAZOO, MI - FEBRUARY 21: People gather and pray at Center Point Church following a mass shooting on February 21, 2016 in Kalamazoo, Michigan. And a father and his 17-year-old son were fatally shot while looking at a pickup truck at a dealership.More news: Chance the Rapper Apologizes for Working With R. Kelly
Dalton never explained his motive, but was deemed competent to stand trial.
Dalton, who was arrested the night of the shootings, initially pleaded not guilty and appeared to be headed to trial until his last-minute plea on Monday.
Dalton allegedly said no.
Throughout the rest of the hearing, Dalton remained in a holding cell with two police escorts, following the hearing by video conference. He also pleaded guilty to killing Dorothy Brown, 74, Mary Jo Nye, 60, Barbara Hawthorne, 68, and Mary Lou Nye, 62 in a Cracker Barrel parking lot.
"I've thought about this quite a lot", he said to Lipsey.More news: Mike LaFleur expected to stay with 49ers after Packers hire brother
A 14-year-old girl was shot in the head during the restaurant shooting and survived, while an eighth person was injured in a residential area.
Dalton, whose charges included six counts of premeditated murder, said he has been wanting this for a long time.
Dalton will be formally sentenced on February 5th.
Days after the shooting, Uber confirmed that Dalton had passed a company background check and that there was no evidence that any warning flags were missed.More news: Clemson overwhelms Alabama to claim second national title in three years
"But I can tell you in private that he has been remorseful during several of my meetings with him".