Williams became more involved in social change as her career progressed, primarily using social media as a medium of expressing her views. In 2016 she posted her support of Black Lives Matter on her Facebook page, voicing her concern about her young nephew being in danger from police officers owing to his skin color. During American tennis player Tennys Sandgren's breakthrough run to the quarterfinals of the 2018 Australian Open, it was revealed that he tweeted insensitive words about the LGBT community, followed members of the alt-right, and referred to an article describing Williams's on-court behavior as "disgusting". Williams responded by tweeting her displeasure, saying, "@TennysSandgren I don't need or want one. But there is an entire group of people that deserves an apology. I can't look at my daughter and tell her I sat back and was quiet. No! She will know how to stand up for herself and others – through my example." Additionally, she attached an image that read, "Maturity is being able to apologize and admit when you're wrong because you know that your mistakes don't define you".
