The Serbian tennis star - who has been dating Jelena for eight years - announced the happy news via Twitter on Wednesday evening (25 September), adding a sweet picture of the couple looking very happy.
26-year-old Novak wrote: "Meet my fiancé and future wife :) So happy! Thank you for wonderful wishes #NoleFam and friends!"
After the pair were inundated with congratulatory messages from fans, Jelena added on her own account: "Thank you all for wonderful wishes! #lucky #blessed #happy."
Jelena is a familiar figure to tennis fans as she's often seen courtside supporting Novak. She's also the director of his charitable foundation, founded in 2007, which supports disadvantaged children in Novak's home country of Serbia.
Earlier this year, Novak paid tribute to his girlfriend at a gala dinner held in London, saying: "Love is the greatest driving force in my life, it can create miracles."
Congratulations to Novak and Jelena!
More celebrities who are engaged in our gallery below!
Copyright: Instagram Mark Wright