Announcing the birth on Instagram, the Torn singer said that her "heart is bursting" following the birth of her baby boy.
She also revealed the name of her newborn, saying: "Welcome to the world... Max Valentine Imbruglia".
Imbruglia, 44, announced that she was expecting in July, telling fans that she fell pregnant using IVF and a sperm donor.
IVF, or in-vitro fertilisation, is a process where the egg and sperm are combined outside of the body and left to fertilise for several days, before it is implanted into the uterus.
She added that she had wanted to be a mother for a "very long time" and felt "blessed" that she was able to conceive.
Soon after the announcement, her celebrity friends publicly gave their congratulations to the singer.
Fellow Aussie Kylie Minogue said: "Welcome Max and congratulations Nat!"
Sophie Ellis-Bextor, known for the hit Murder on the Dancefloor said: "Yay!!! Hello, Max! Welcome indeed. So glad you're here safe and sound. Congratulations, mama!!"
Louise Redknapp, who found fame in girl group Eternal, said: "Congratulations babe so happy for you xxxxx."
The Australian singer found fame in the early 1990s, when she starred in the cult soap Neighbours, as Beth Brennan.
Once she left the show, she began her music career by releasing a cover of the song Torn by Ednaswap, bringing her international acclaim.
She has also starred in a number of movies, including the first Johnny English film, and has been a judge in both the UK and Australian versions of the X Factor.
Imbruglia was married Australian musician Daniel Johns but they split in 2008. She also previously dated Friends star David Schwimmer in the 1990s.