Floyd, a 46-year-old black man, died unarmed after pleading for help as a white police officer knelt on his neck for several minutes while pinning him to the ground.
Floyd was declared dead at a nearby hospital soon after, according to authorities.
Former San Francisco 49ers quarterback Colin Kaepernick, a leading figure in the movement against systemic racial injustice, threw his support behind the demonstrations which began in Minneapolis this week, and have spread to Louisville, Kentucky, Memphis, Tennessee, and elsewhere around the country.
“The cries for peace will rain down, and when they do, they will land on deaf ears because your violence has brought this resistance.
“We have the right to fight back! Rest in power George Floyd.”
In 2016, Kaepernick famously knelt during the national anthem to protest police brutality and his iconic protest has been used to show the juxtaposition of Floyd’s death.
These were thoughts echoed by Stephen Jackson, a former NBA player and friend of Floyd.
Jackson, who called Floyd “twin”, said he will head to Minnesota in order to give his friend a voice.
“This is not the way he was supposed to go,” he told CNN’s Newsroom.
“He didn’t deserve that, but the way that people are supporting him, standing up for him — the way I’m going to stand up and support him — his death will not be in vain.
“What is justice? I can’t even answer that question. I’ve seen so many black men get killed, officers get laid off jobs with pay, no jail time.”
Four Minneapolis police officers involved in Floyd’s death have been fired — but his family says they want murder charges against them.
“We will work tirelessly to use our voices to influence change, encourage healing, and promote thoughtful action as we move forward,” it wrote.
NFL’s Minnesota Vikings also said it was saddened by the tragedy which occurred close to its stadium.
“Our thoughts are with the George Floyd family and all individuals who have been affected by this tragedy.”
Homero De La Fuente contributed to this report.