Novak, who is currently on holiday with Jelenain Athens, revealed the exciting news on Twitter writing, "Jelena is pregnant!!! We will be parents soon! #blessed."
Along with the comment, the 26-year-old Tennis champion added a picture of himself and Jelena staring lovingly into each other's eyes against a sunset backdrop.
Novak also shared his news on his Facebook fan page.
"My dear friends," he wrote. "You've been with me through many tough and good times in my career.
"I've been blessed to travel the world, play the most beautiful sport that brings me a lot of excitement and joy; I am happy, loved and healthy. Jelena and I are truly blessed to soon become parents! My love is pregnant!"
The post quickly garnered 100,000 likes and a host of congratulatory comments.
Novak Djokovic and Jelena Ristic in front of The Acropolis
Novak and Jenna announced their engagement in September.
The Serbian sportsman revealed the happy news by tweeting, "Meet my fiancée and future wife :) So happy! Thank you for wonderful wishes".
Alongside the message, Novak shared a photo taken with his beautiful bride-to-be, who is seen affectionately kissing him on the cheek.
Love match: Tennis ace Novak Djokovic announces his engagement
The elated couple, who live together in Monte Carlo, have been dating for eight years. Delighted Jelena, 27, has also thanked fans for their "wonderful wishes".