Derek Chauvin was found guilty of using his position to take life, ITV News US Correspondent Emma Murphy reports
The verdict, which was reached by a jury after less than a day of deliberations and read out on Tuesday afternoon US time, triggered celebrations across the city as crowds flooded the streets with banners and cars blared their horns.
Mr Floyd died on May 25 last year after Chauvin, a 45-year-old white officer, was seen on video kneeling on the 46-year-old black man’s neck for about nine-and-a-half minutes.
The footage drew outrage across the US and triggered worldwide protests and violence last summer.
The jury, which consisted white people and six black or multi-racial people, found Chauvin guilty of all three of his charges: second-degree unintentional murder, third-degree murder and second-degree manslaughter.
Watch the moment the guilty verdicts are delivered
Little reaction could be seen in Chauvin's face, which was obscured by a face mask, as the verdicts were read out.
The most serious charge, second-degree murder, carries up to 40 years in prison. Sentencing will take place in two months' time.
Bail was revoked and Chauvin was led away with his hands cuffed behind his back. He will be kept in custody until sentencing.
Mr Floyd's family who had gathered at a Minneapolis conference room could be heard cheering and laughing.
A woman bursts into tears as she says "they see us" upon learning about Chauvin's guilty verdicts:
Mr Floyd's brother Philonise Floyd told reporters at a press conference: "I feel relieved today that I finally have the opportunity to get some sleep. A lot of days that I pray and I hope and I was speaking everything into existence. I said: I have faith that he will be convicted."
He continued: "Today, you have cameras all around the world to see and show what happened to my brother.
"It was a motion picture, the world seeing his life being extinguished and I could do nothing but watch, especially in the court room over and over and over again as my brother was murdered.
"Times, they getting harder every day," Mr Floyd's brother said wiping away tears.
He added: "Imma put up a fight every day, because I'm not just fighting for George anymore, I'm fighting for everybody around this world."
Mr Floyd's brother Philonise Floyd says he can finally get some sleep after the guilty verdict:
Mr's Floyd's family attorney Ben Crump said: “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."
Crowds can be seen celebrating outside the court and outside Cup Foods store, where Mr Floyd died.
ITV News Global Security Editor Rohit Kachroo, who was outside Cup Foods, described seeing people screaming "Black Lives Matter" and a man on the floor in tears shouting "They see us".
ITV News Global Security Editor Rohit Kachroo is at the site where George Floyd died, where people are celebrating the court verdict:
Mr Floyd's girlfriend Courteney Ross, who joined in the celebrations, told a crowd: "Floyd also loved our city because he thought it was so beautiful and diverse. I agreed with him but I warned him about that because though we are so diverse, we are also so separated."
She continued: "I know it would be his dream to have this event bring us together. He has never been about divisiveness, he has always been about inclusiveness. Floyd would not forget those who were forgotten."
Mr Floyd's girlfriend Courteney Ross said it would be Mr Floyd's "dream" to bring people together in this moment:
US President Joe Biden, Vice President Kamala Harris Harris and first lady Jill Biden called members of Mr Floyd's family moments after the verdict, according family attorney Mr Crump.
Speaking to the nation, Biden said Mr Floyd's death was “a murder in the full light of day and it ripped the blinders off” for all the world to see the problems with race and policing in the US.
He said the verdict can be a giant step forward for the country against systemic racism and that it is so important to ensure black and brown people don’t fear the police.
Vice President Kamala Harris said the nation still must work to reform the criminal justice system. “A measure of justice isn’t the same as equal justice,” she said.
Biden told the family, “Nothing is going to make it all better, but at least now there is some justice.” He added, “We’re all so relieved,” according to a video of the call posted on Twitter by Mr Crump.
UK Prime Minister Boris Johnson reacted to the verdict: “I was appalled by the death of George Floyd and welcome this verdict.
“My thoughts tonight are with George Floyd’s family and friends.”
US Correspondent Emma Murphy, who is at the scene outside the court, said people are "utterly ecstatic":
The charges were brought against the ex-police officer after Mr Floyd died during an arrest outside Cup Foods store on May 25 last year. Police tried to arrest Mr Floyd after he allegedly tried to give a shop worker a counterfeit $20 note.
Video showing Mr Floyd struggling with police drew outrage across the US. The footage shows police trying to put the 46-year-old in a car, but Mr Floyd panicks and pleads that he is claustrophobic. They they pin him to the pavement.
Later in the video, Chauvin's knee is shown to be on Mr Floyd's neck as the 46-year-old gasps repeatedly, "I can't breathe" and as members of the public yelled at the police officer to get off him.
Prosecutors played the video to jurors at the start of the trial, during opening statements, with Jerry Blackwell telling them to “Believe your eyes.” It was shown over and over, analysed one frame at a time by witnesses on both sides.
Due to tensions in the city, the jury deliberated in a downtown courthouse surrounded by concrete barriers and razor wire, as racial tensions bubbled in the city.
The jurors’ identities are being kept secret and will not be released until the judge decides it is safe to do so.
Prosecutor Steve Schleicher in his closing statement said Chauvin knew the risks of positional asphyxia, had warnings from bystanders, ignored a fellow officer's advice to roll Mr Floyd to the side in a recovery position, and failed to provide CPR when Mr Floyd fell unconscious.
He said Chauvin "had to know" he was squeezing the life out of Mr Floyd as he had his knee on his neck.
He said Mr Floyd's heart failed because of Chauvin's use of force, not because of drug use or heart disease, as the defence argued. He repeated the statement by lung and critical care specialist Martin Tobin that Mr Floyd died due to lack of oxygen while being pinned down.
The prosecutor also argued Mr Floyd being big and being on drugs was not a "threat", but a "risk", and those factors did not justify the police officer's use of force.
Concluding, Mr Schleicher said: “This wasn’t policing. This was murder.”
But defence lawyer Eric Nelson argued in his closing statement Chauvin did what any "reasonable" police officer would have done as he was in a "dynamic" and "fluid" situation where a large man was struggling with three officers.
Racial tensions have been bubbling in the city of Minneapolis. In recent days, there has been fresh outrage over a 20-year-old black man, Daunte Wright, who was shot dead by police on April 11 in the nearby Minneapolis suburb of Brooklyn Centre.
The case is one of the most high-profile court cases in US history, after Mr Floyd's death sparked a worldwide movement against police brutality and racism.
ITV News Correspondent Robert Moore says the verdict will have a huge impact on the future of policing in the US:
A host of celebrities have also welcomed the guilty verdict for Chauvin.
Mariah Carey tweeted “Hallelujah!!!!!!!!” in response to the news, before adding: “A beginning.. a small grain of hope for our future.”
Chris Evans, an actor known for playing Captain America in the Marvel films, said: “Justice. Sending love to George Floyd’s family and friends.”
Zendaya posted a picture of Mr Floyd to her Instagram.
Singer Justin Timberlake said the verdict represented “the first step in a long line of injustice against the Black community, often with no consequences”.
He added: “The work is not nearly done. While there are many more families waiting for justice, my heart is with George Floyd’s family right now.”
British F1 driver Lewis Hamilton shared his reaction, describing the verdict as “monumental”.
He added: “But this is just one step on the path towards a more equal society. Since George’s death, so many other Black people have died at the hands of the police and we must ensure the momentum of today continues. The fight isn’t over, and there is more to be done.”
Hawaii Five-0 actor Daniel Dae Kim, who has been condemning a spike in violence against the Asian community in the US, said: “Today is a day we will all remember. Prayers for George Floyd and his family.”
Poet Amanda Gorman, who rose to international attention following her address during Joe Biden’s inauguration, said: “A reminder that victory would be George Floyd being alive. Every day Black Americans worry if they will be next is another day without justice.”
And Bridgerton’s Nicola Coughlan tweeted: “Thank God. #BlackLivesMatter.”