Blanchett's ancestry includes English, some Scottish, and remote French roots.
Blanchett was born on 14 May 1969, in the Melbourne suburb of Ivanhoe. She is the middle of three children; her older brother is a computer systems engineer, and her younger sister is a theatrical designer. Her Australian mother, June (born Gamble), worked as a property developer and teacher, and her American father, Robert DeWitt Blanchett, Jr., a Texas native, was a United States Navy petty officer who later worked as an advertising executive. The two met when Blanchett's father's ship broke down in Melbourne. When Blanchett was 10, her father died of a heart attack, leaving her mother to raise the family on her own.
Blanchett has described herself as being "part extrovert, part wallflower" during childhood. She had a penchant for dressing in traditionally masculine clothing, and went through goth and punk phases during her teenage years, and shaved her head at one point.