Serena, 37, was joined by her husband Alexis Ohanian and their one-year old daughter Olympia for the meet and greet.
She posted a photo of herself on Instagram in a regal state room at the Frogmore Cottage where Harry, 34, and Meghan, 37, reside.
Serena also shared an Instagram boomerang of her dancing around the elegant space. It was to celebrate her passing eleven million followers on the social networking app.
She did this before competing in The French Open. Her next match takes place on Monday, May 27.
Serena and Meghan have been good friends for a long time. The tennis superstar and her hunky husband attended HRH's wedding to Harry in May of last year.
Harry and Meghan have not revealed who they have named godparents to their newborn son Archie just yet. She welcomed him into the world on Monday, May 6.
Do you think Meghan will name Serena as Archie's godmother? Sound off in the comments!