This was made known by the tennis superstar when she made an announcement in the form of a sweet poem she shared on Reddit, the website co-founded in 2005 by 33-year-old Ohanian.
“I came home a little late, someone had a bag packed for me and a carriage awaited destination. Rome!
“To escort me to my very own 'charming'. Back to where our stars first collided,” wrote Williams on her recently verified account on Reddit.
“And now it was full circle, at the same table we first met by chance.This time he made it not by chance but by choice.
“Down on one knee, he said four words and I said yes.''
A report by the News Agency of Nigeria (NAN) states that the poem was compiled with an adorable cartoon of the couple.
Ohanian is said to have replied to Williams' post by saying “And you made me the happiest man on the planet.''
Alex shared Williams' post on Facebook with his own jubilant announcement: “She said yes.''
Williams' media representative has also confirmed the engagement.
Another report by NAN says that the couple have kept their relationship a bit secret, with Williams sharing just a few Instagram photos of them enjoying time together with friends.
The tennis star had made headlines by chasing down a mugger who grabbed her phone while she was dining with Ohanian in San Francisco in November 2015.
This year, Williams won her seventh Wimbledon singles title and 22nd Grand Slam singles title, but unfortunately dropped to world number two ranking.
However, the Two won't have much time to celebrate just yet as Williams is currently in New Zealand preparing to compete in the ASB Classic.
Ohanian is an American internet entrepreneur, activist, investor, and best-selling author born in the Brooklyn borough of New York City and based in San Francisco according to NAN reports.
Reddit is a social media community where users group around topics, news articles and discussion points, rather than around people they know in offline life.
Reddit was founded in 2005 by Ohanian alongside a college friend, Steve Huffman.