The 2017 Australian Open champion was wearing a green Atelier Versace gown. She smiled for the cameras, posing with Ohanian, who is a co-founder of Reddit.
On April 19 Williams confirmed that she is pregnant and expecting her first child later this year.
The 35-year-old player won her latest title in January while two months pregnant, and is expected to sit out the rest of the year, but her spokesperson has said Williams will be back on the tennis circuit in 2018.
This year’s event was themed “Rei Kawakubo/Comme des Garçons: Art of the In-Between,” an homage to highly structured creations of the Japanese designer and her avant-garde label.