The 43-year-old actress has been married to screenwriter Upton for 15 years. Blanchett says they got engaged within weeks of meeting each other as they knew they were perfect for one another, reported Sun online.
"The most romantic moment in my life was meeting my husband. Love at first sight? Yes, it was. He proposed two weeks after we met.
A straight, old-fashioned proposal," she said.
The Australian beauty, who has three children, Dashiell, 11, Roman, eight, and Igantius, four, with Upton, didn't have time for a honeymoon after getting married because of her busy Hollywood career, so instead made a romantic pact with her husband.
"We didn't have time for a honeymoon because I had to leave Australia for England to film 'Elizabeth'. It meant that I was on my own, in places like Newcastle. So we thought we'd stretch it out over the next 50 years in installments.
"We have taken it when we can. I did the film 'The Talented Mr Ripley' in Italy and only worked about two days a week during a Roman summer, so that was a fantastic place to catch up on romance," she added.