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, was posted with the caption "Unity is strength. #BlackLivesMatter".
Players reportedly requested the picture during training on Monday.
Manchester United players Paul Pogba and Marcus Rashford 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.
- Jadon Sancho & Marcus Thuram join protests against racism
- George Floyd death: Violence erupts on sixth day of protests
- The last 30 minutes of George Floyd's life
Former San Francisco 49ers quarterback Colin Kaepernick first protested against racial injustice and police brutality by kneeling down during the American national anthem in the summer of 2016. That gesture has since become symbolic to the Black Lives Matter movement.
United midfielder Pogba said in a passionate Instagram post that he felt "felt anger, pity, hatred, indignation, pain and sadness".
The French World Cup winner added: "Sadness for George and for all black people who suffer from racism EVERY DAY! Whether in football, at work, at school, ANYWHERE! This has to stop, once and for all. Not tomorrow or the next day, it has to end TODAY!
"Violent acts of racism can no longer be tolerated. I can't tolerate, I won't tolerate, WE WON'T TOLERATE.
"Racism is ignorance, LOVE is intelligence, STOP the silence, STOP racism."
United team-mate Rashford said he had been "trying to process what is going on in the world".
The England striker 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."
Numerous Liverpool players tweeted the picture of themselves kneeling at Anfield, including defenders Virgil van Dijk,Joe Gomez, Andrew Robertson and Trent Alexander-Arnold, and midfielders Georginio Wijnaldum and James Milner.
German FA praises protesting players despite investigation
In Germany, Jadon Sancho and Achraf Hakimi of Borussia Dortmund, Weston McKennie of Schalke, and Marcus Thuram of Borussia Monchengladbach made on-field protests at the weekend
The four players are being investigated by the German Football Association (DFB) for breaching rules over making political statements on the field of play.
But DFB president Fritz Keller said he felt "respect and understanding" for them
He said: "I have great respect for players who have an attitude and show their solidarity. I wish for such mature players and I am proud of them.
"Morally, I can absolutely understand the actions. What happened in the USA can leave anyone cold.
"When people are discriminated against because of the colour of their skin, this is intolerable. If they die because of their skin colour, then I am deeply shocked. The victims of racism need solidarity from us all.
"The DFB and German football as a whole, through their broad commitment, show time and again and in many forms, events and facets their clear NO to racism, discrimination and all forms of violence."
In relation to the investigation, DFB vice-president Rainer Koch said: "The rule is the immediate phase of the game should be kept free of political statements. It remains to be seen whether sanctions are necessary in the cases."
'We have had enough'
British sprinter Dina Asher-Smith, Liverpool striker Rhian Brewster and tennis stars Serena Williams, Coco Gauff and Naomi Osaka were among the sportspeople to speak out about Floyd's death.
And basketball legend Michael Jordan said he was "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 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, 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."