The incident, which was live-streamed on Facebook by a bystander, saw Floyd protesting that he could not breathe, before he fell unconscious.
A short time later, he was pronounced dead in hospital.
Floyd was arrested as he matched the description of a suspect who was accused of trying to use a counterfeit $20 bill at a grocery store.
When police officer Derek Chauvin knelt on Floyd's neck, he was unarmed and according to video evidence, he did not resist arrest.
As the video began to circulate online following Floyd's death, protesters took to the streets of Minneapolis with chants of "I can't breathe" – echoing some of the 46-year-old's last words.
Since then, protests across the city of Minneapolis have escalated into complete chaos, with protests also emerging in New York, Atlanta, Los Angeles, and Washington DC.
While some protests have remained peaceful, others have escalated, leading to arson and looting. As protests have become more chaotic, police have responded with tear gas, stun guns, and rubber bullets.
Since the protests began, Chauvin, the policeman involved, has been arrested and charged with third degree murder and manslaughter. At the time of reporting, the three other police officers involved in the arrest of Floyd have not yet been charged.
Across the United States, protesters are now calling for justice and an end to police brutality.