Novak announced the couple's baby joy via Twitter on Wednesday (22 October) and revealed that they have named their son Stefan.
Former Wimbledon winner Novak tweeted: "Stefan, our angel baby was born! I am so proud of my beautiful wife Jelena. Thank you so much for your love and support. We love you all"
And how did World No. 1 Novak celebrate? By hitting the tennis courts!
Novak shared a picture of himself practising on the courts, saying: "First practice as a dad. Not a bad hit for an old man."
First practice as a dad. Not a bad hit for an old man. pic.twitter.com/joOuGpGjYk— Novak Djokovic (@DjokerNole) October 22, 2014
It's been a busy few months for Novak and Jelena, as the high school sweethearts tied the knot in July in Montenegro, after eight years of dating.
Jelena, who is often courtside supporting Novak in his tennis tournaments, got engaged to the tennis star in September last year.
The loved-up couple announced they were expecting their first child together in April while holidaying in Athens.
More stars who have welcomed babies this year:
Copyright: Rex Features WENN/Matthew Taylor/Daniel Deme/Josiah True/Matthre Taylor/Joe