Blanchett's husband is playwright and screenwriter Andrew Upton, who she met in 1996 while she was performing in a production of The Seagull. It was not love at first sight, however; "He thought I was aloof and I thought he was arrogant", Blanchett later remarked. "It just shows you how wrong you can be, but once he kissed me that was that." The two were married on December 29, 1997. Their first child, Dashiell John, was born on December 3, 2001; their second child, Roman Robert, was born on April 23, 2004 and on April 13, 2008, they welcomed their third son, Ignatius Martin "Iggy" Upton, in Sydney.

After making Brighton, England their main family home for much of the early 2000s, she and her husband returned to their native Australia. In November 2006, Blanchett stated that this was due to a desire to decide on a permanent home for her children, and to be closer to her family as well as a sense of belonging to the Australian (theatrical) community.[11] She and her family live in "Bulwarra", an 1877 sandstone mansion in the harbourside Sydney suburb of Hunters Hill. It was purchased for $10.2 million Australian dollars in 2004 and underwent extensive renovations in 2007 in order to be made more "eco-friendly".[12][13]

In 2006, a portrait of Cate Blanchett and family painted by McLean Edwards was a finalist in the Archibald Prize, which is awarded the "best portrait painting preferentially of some man or woman distinguished in Art, Letters, Science or Politics".[14]

Blanchett is a Patron of the Sydney Film Festival. She works as the face of SK-II, the luxury skin care brand owned by Procter & Gamble. In 2007, Blanchett supported the web-based campaign whoonearthcares.com — urging people to express their concerns about climate change in Australia.