The Serbian sportsman announced the happy news on Wednesday, tweeting, "Meet my fiancée and future wife :) So happy! Thank you for wonderful wishes".
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Alongside the message, Novak shared a photo taken with his beautiful bride-to-be, who is seen affectionately kissing him on the cheek.
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".
She works as the chief executive officer of the Novak Djokovic Foundation, which helps children from disadvantaged communities to play and develop in safe settings, and has been a constant fixture courtside throughout Novak's career.
The happy news comes just days after Novak, a six-time Grand Slam champion, became the ninth player in history to reach 100 weeks as the world number one.
Now set to marry his stunning long term girlfriend, he will feel every bit a champion off the court too.