The US tennis star posted that she found herself feeling wary of law enforcement during a recent journey with her teenage nephew.
Williams said that when they drove by a patrol car she remembered a woman whose boyfriend was fatally shot by police.
She is the latest athlete to speak out about friction between law enforcement and the black community in the US.
In Tuesday's Facebook post, Williams, 35, wrote that she had asked her 18-year-old nephew to drive her somewhere so she could work during the journey.
