A jury has unanimously convicted Derek Chauvin of the murder of George Floyd.
Former Minneapolis police officer Chauvin had denied charges of second-degree murder, third-degree murder and second-degree manslaughter.
But after 10 and a half hours of deliberations, the jury convicted the 45-year-old on all counts.
Chauvin, whose face was obscured by a COVID mask, showed little emotion as the guilty verdicts were read out.
He was remanded in custody, handcuffed and led out of the courtroom.
Under Minnesota's sentencing guidelines, he faces 12.5 years in prison for his murder conviction as a first-time offender but prosecutors could seek a maximum of 40 years if the judge determined there were "aggravating factors".
Outside the court building, a crowd of several hundred people erupted in cheers when the verdicts were announced.
At Minneapolis's George Floyd square, where Mr Floyd was killed and which is now named after him, people screamed, applauded and wept.
The site has become a rallying point for racial justice protests.
US President Joe Biden, First Lady Jill Biden, and Vice President Kamala Harris called Mr Floyd's family moments after the verdict.
Mr Biden told them: "Nothing is going to make it all better, but at least now there is some justice.
"We're all so relieved."
Mrs Harris promised them: "We're going to make something good come out of this tragedy."
Later, speaking from the White House, Mr Biden said Chauvin's conviction "can be a giant step forward" for the nation against systemic racism.
Ben Crump, a lawyer for Mr Floyd's family, said afterwards: "America, let's pause for a moment to proclaim this historical moment, not just for the legacy of George Floyd but for the legacy of America.
"This is a victory for those who champion humanity over inhumanity, those who champion justice over injustice."
Mr Floyd, a 46-year-old black man, died while being restrained by Chauvin, who is white, during his arrest in the US city in May 2020.
Video filmed by bystanders showed Chauvin's knee pressed into Mr Floyd's neck and back for almost nine minutes as he gasped for breath.
The footage shocked the world and sparked global protests about racism and police brutality.
An unarmed Mr Floyd had been apprehended after allegedly trying to use a counterfeit $20 note to buy cigarettes at a neighbourhood shop in Minneapolis - something senior police officers had said would not normally warrant arrest.
However, Chauvin's lawyer argued the former officer had acted reasonably because Mr Floyd kept struggling and he had actually died due to drugs found in his system - both arguments were dismissed by the jury's guilty verdict.
What happened on 25 May 2020?
After Donald Williams watched the last moments of George Floyd's life, he called the police because he believed he had witnessed a murder.
And now a jury in Minneapolis has agreed with that assessment.
But what Mr Williams witnessed from the pavement on 25 May last year was also seen by millions of people around the world within hours of Mr Floyd's death.
People using video phones captured the moment officers approached him outside the shop, to the moment his limp body was pulled on to a stretcher and carried into an ambulance.
Throughout the footage, Mr Floyd appeared upset, scared, uncooperative but never violent.
One of the key recordings came from the then 17-year-old Darnella Frazier, who told the court she stays awake some nights apologising to the memory of Mr Floyd for not intervening.
Who can say how differently this story may have played out had the teenager not recorded and shared on social media the anguished death of Mr Floyd?
Her mobile phone video - those infamous eight minutes and 46 seconds of footage - exposed the reality of one man's interaction with law enforcement and told a wider story of a history of police brutality and racial inequality in America.
A pivotal moment in US history?
It also made Chauvin's murder trial a landmark moment for the country.
It is rare for any police officer to be charged with murder or manslaughter when they kill someone in the line of duty. Only about a third of those who are charged are convicted.
Before Chauvin, only one police officer in Minnesota had been convicted of murder - and he was a Muslim Somali-American.
Chauvin's conviction will be welcomed by those who have been calling for a reckoning in the way minority communities, in particular, are treated by police. But it will be seen as only one step on a long road.
The Police Officers' Federation of Minneapolis said after the verdict: "We would like to thank the jury for their dedicated work and we understand they had an enormous burden. We also want to reach out to the community and still express our deep remorse for their pain, as we feel it every day as well.
"There are no winners in this case and we respect the jury's decision. We need the political pandering to stop and the race baiting of elected officials to stop. In addition, we need to stop the divisive comments and we all need to do better to create a Minneapolis we all love.
"To all the residents of Minneapolis, the POFM stands with you, and not against you. Looking forward to working together for a safer, better tomorrow."
Officers had been called to the scene on the day Mr Floyd died over reports of the use of a counterfeit $20 note. The police chief of Minneapolis said that was an offence that would not usually merit arrest.
https://news.sky.com/story/george-f...ficer-derek-chauvin-guilty-of-murder-12280899