At one point, a man in the courtroom lunged at Payton Gendron, who had pleaded guilty to 15 state charges including murder and terrorism motivated by hate stemming from the May 14 mass shooting in Buffalo, a city of about 277,000 people.
Thirteen relatives of victims spoke during the hearing including Simone Crawley, who called Gendron, 19, a "cowardly racist".
Wednesday's sentence, which was expected because the state does not employ the death penalty, was given by Erie County Court Judge Susan Eagan.
Wearing an orange jumpsuit and glasses, Gendron apologised to the families of his victims, whose ages ranged from 20 to 86, expressing regret for his actions and hope that his crime will not inspire copycat attacks.
The rampage was one of the deadliest in a series of mass shootings in recent years in a country that has grown accustomed to such crimes and where racial tensions continue to simmer.
"I am very sorry for all of the pain I forced all of the victims and their families to suffer through," said Gendron, who was standing and looking downward while speaking.
"I did a terrible thing that day. I shot and killed people because they were Black."
Gendron had streamed live video of the attack on social media after posting a racist screed online detailing his inspiration from other racially motivated mass killings, authorities said.
A woman screamed in an agonised tone inside the courtroom after Gendron finished his statement.
The hearing was halted briefly after an unidentified man lunged at Gendron, who was sitting at a table in the courtroom with his lawyers as a woman named Barbara Massey Mapps made an emotional statement. Her 72-year-old sister, Katherine Massey, was among those killed.
The man pushed Massey Mapps aside and took several running steps toward Gendron before police and lawyers restrained him and led him away. Officers grabbed Gendron and rushed him out of the courtroom.
Crawley, whose 86-year-old grandmother Ruth Whitfield was killed, said Gendron made his victims immortal instead of gaining support for his hateful cause. Authorities have said Gendron promoted a racist conspiracy notion that white people are being replaced by minorities in America and elsewhere.
"We as a people are unbreakable," Crawley said.
"I don't wish the death penalty on you," said Wayne Jones, whose 65-year-old mother Celestine Chaney was gunned down. "I wish they keep you alive so you have to suffer with the thought of what you did for the rest of your life."
While New York state no longer uses capital punishment, Gendron still could receive a death sentence if convicted of pending federal hate crime and firearms charges to which he has pleaded not guilty. Gendron was 18 at the time of the attack.
Erie County District Attorney John Flynn and Buffalo Mayor Byron Brown called Gendron's apology too little and too late.
"I anticipate what he said today was to save his life in federal court," Flynn said after the hearing.
Gendron's defence lawyer, Brian Parker, told a news conference that his client was remorseful.
"We hope that knowing he will never be free again will offer some small bit of comfort to those he has hurt so much," Parker said.
Prosecutors have said the gunman targeted a Tops Friendly Markets supermarket in a Black neighbourhood of Buffalo, about 320 kilometres from his home in Conklin, New York, intending to kill as many Black people as he could with an assault weapon. In addition to the 10 people who were killed, three others were wounded.
Gendron faces 27 federal charges. His lawyers have sought a plea deal relating to these in an effort to avoid a possible death sentence.
The US Justice Department has not disclosed what punishment it would seek if Gendron is convicted.
