Liverpool players took a knee around the centre circle at Anfield in a message of support following the death in police custody of African-American George Floyd in Minneapolis.
The picture featuring 29 Reds players came with the caption “Unity is strength. #BlackLivesMatter”.
Players reportedly requested the picture during training on Monday.
England internationals Marcus Rashford and Jadon Sancho added their voices to worldwide protests against racism.
Protests have been held after Floyd, an unarmed black man, died on 25 May after being restrained by white Minneapolis police officer Derek Chauvin, who kneeled on his neck for almost nine minutes to pin him down.
Chauvin has since been charged with his murder and sacked.
Former San Francisco 49ers quarterback Colin Kaepernick first protested against racial injustice and police brutality by kneeling down during the United States national anthem in the summer of 2016. Since then, that gesture has become symbolic to the Black Lives Matter movement.
Manchester United and England footballer Rashford said he had been “trying to process what is going on in the world”.
He added: “At a time I’ve been asking people to come together, work together and be united, we appear to be more divided than ever.
“People are hurting and people need answers. Black lives matter. Black culture matters. Black communities matter. We matter.”
Liverpool players that tweeted the same picture and message included defenders Virgil van Dijk and Joe Gomez, full-back Trent Alexander-Arnold, midfielder Georginio Wijnaldum, as well as James Milner and Andrew Robertson.
British 200m world champion sprinter Dina Asher-Smith had tweeted on Thursday: “Racism, police brutality… all of this is something we all have to be vocal about. Irrespective of our race or nationality.
“RIP George Floyd. Heartbreaking and sickening to have to be saying RIP to another black person in these circumstances.”
On Sunday, England footballer Sancho unveiled a “Justice for George Floyd” T-shirt after scoring for Borussia Dortmund against Paderborn and Marcus Thuram took a knee after scoring for Borussia Monchengladbach.
Liverpool striker Rhian Brewster and tennis stars Serena Williams, Coco Gauff and Naomi Osaka also spoke out about Floyd’s death.
‘We have had enough’
Basketball legend Michael Jordan says he is “deeply saddened, truly pained and plain angry”.
“I see and feel everyone’s pain, outrage and frustration,” he added. “I stand with those calling out the ingrained racism and violence toward people of colour in our country.”
“We have had enough.”
Vanessa Bryant, widow of basketball legend Kobe, shared an image of her late husband wearing an “I Can’t Breathe” T-shirt.
“My husband wore this shirt years ago and yet here we are again,” she wrote.
“Life is so fragile. Life is so unpredictable. Life is too short.”
F1 drivers answer Hamilton’s call
Formula 1 drivers Charles Leclerc, Lando Norris, Carlos Sainz, George Russell and Daniel Ricciardo all issued anti-racism messages on social media after reigning F1 world champion Lewis Hamilton criticised those in his industry for not speaking out.
“I’m one of the only people of colour and yet I stand alone,” the Briton, 35, who is the only black F1 driver, wrote on Instagram.
“I would have thought by now you would see why this happens and say something about it but you can’t stand alongside us.”
Leclerc said he had been “completely wrong” not to speak out previously, saying he had not done so because he felt “out of place and uncomfortable”.
Hamilton’s Mercedes team said in a statement they “stand with Lewis” and were “deeply saddened by the recent developments and hope to see a de-escalation soon”.
They added: “Tolerance is an elementary principle of our team and we are enriched by diversity in all its forms. We welcome and encourage people from all races, cultures, religions, philosophies and lifestyles.
“We condemn every form of discrimination as we work together to drive change forward.”