The Duke of Cambridge is leading the way as social media accounts across British and European sport have been shut down in a united front against online abuse.
Since it was first announced, the boycott, which runs for three days over the weekend, has grown as other sport governing bodies, sponsors, partners, broadcasters and media outlets have come on board.
A coalition of football's largest governing bodies and organisations, including the Football Association, Premier League and EFL, were among those to go silent on social media in a show of solidarity against sustained, sickening and spiralling abuse.
European soccer governing body UEFA is also taking part, as well as Scottish and Irish football, England Rugby, Scottish Rugby, British Cycling, the Rugby Football League, British Horseracing, the England and Wales Cricket Board, the Lawn Tennis Association, International Tennis Federation and others.
In January, Prince William, who is president of the FA, hit out at racist abuse in football, describing it as "despicable" and saying it "must stop" after several black players were targeted online.
Shortly ahead of 3pm, in a tweet, signed W for William, the future king pledged his support.
The post, from the Kensington Royal account, read: "As President of the FA I join the entire football community in the social media boycott this weekend. W."
Earlier, Manchester United confirmed the club had banned six fans for abusing Tottenham's Son Heung-min and revealed online abuse aimed at their players has increased 350 per cent.
Chelsea also announced on Friday a decade-long ban to a supporter for anti-Semitic posts.
Formula One had issued a statement supporting the boycott, saying: "We continue to work with all platforms and our own audiences to promote respect and positive values and put a stop to racism."
However, the organisation will not take part, having discussed the topic with all 10 teams ahead of this weekend's Portuguese Grand Prix.
Posts on the official F1 Twitter feed continued following 3pm, with coverage of practice sessions at the Algarve International Circuit.
Sir Lewis Hamilton, though, will join the boycott, along with Williams driver George Russell.
Seven-time world champion Hamilton has 22 million followers on Instagram and more than six million on Twitter.
In a post ahead of the boycott, Hamilton said: "To stand in solidarity with the football community, I will be going dark on my social media channels this weekend.
"There is no place in our society for any kind of abuse, online or not, and for too long it's been easy for a small few to post hate from behind their screens.
"While a boycott might not solve this issue overnight, we have to call for change when needed, even when it seems like an almost impossible task. Sport has the power to unite us.
"Let's not accept abuse as part of sport, but instead, let's be the ones who make a difference for future generations."
Australian Associated Press