Dallas Cowboys quarterback Dak Prescott has pledged $1m to “improve police training and address systemic racism” in the United States.
It comes in the wake of the death of George Floyd, an unarmed black man, while being restrained by a white Minneapolis police officer on 25 May.
Protests have been held across the United States as well as globally.
“As a black multiracial American, I am disgusted and unsettled,” Prescott, 26, wrote on Instagram on Wednesday.
“I try to understand and find the positive in every situation or aspect of my life.
“As our communities take action, protesting and fighting for the justice of George Floyd and every black life, I am with you!”
Prescott said he had the “utmost respect” for the police, but added: “You need to hold your own accountable! Each of you are as guilty as the men who stood beside Derek Chauvin if you do not stand up against the systemic racism plaguing our police forces nationwide.”
Chauvin, the police officer who kneeled on Floyd’s neck for almost nine minutes to pin him down, has since been charged with murder and been sacked.
On Wednesday, the other three officers involved were charged with aiding and abetting murder.