Cate Blanchett is married to screenwriter Andrew Upton
Blanchett, 32, who was Oscar-nominated for her role in the movie Elizabeth, had Dashiell John on Thursday, said her publicist Lisa Kasteler.
Blanchett is married to screenwriter Andrew Upton, and Kasteler said the baby and his parents were all doing well.
Upton and Blanchett met in 1997 whilst working on the movie Thank God He Met Lizzie. They married a year later.
Blanchett can currently be seen alongside Bruce Willis and Billy Bob Thornton in comic crime caper Bandits.
Audiences will then see her in the hotly-anticipated first movie of The Lord of the Rings, in which she plays Elf Queen Galadriel.
Next year, she will be seen in the World War II drama Charlotte Gray - the story of a Scottish woman who joined the French Résistance.
Blanchett's role in the film Elizabeth made her an international household name.
Yet, until then, she had been a little-known actress who had spent much of her career treading the boards of Sydney's theatreland.
In 1997 her film career took off, with her appearance in Bruce Beresford's Paradise Road and Thank God He Met Lizzie.
Stage
But it was not until her role alongside Ralph Fiennes in Gillian Armstrong's Oscar and Lucinda later that year, that Hollywood really began to notice Cate Blanchett.
The film was not a huge success, but alerted movie executives to Blanchett's talent and landed her the lead role in Elizabeth.
Blanchett has also followed a host of screen stars onto the London stage, including her fellow countrywoman Nicole Kidman, when she appeared in Plenty in 1999.