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The 24-year-old, who defended her British title in the 58kg category in June, tested positive for a metabolite of stanozolol at the same competition.
She contested the charge on the grounds that the positive test came from taking medication for a swollen foot.
Head of UK Anti-Doping Nicole Sapstead said Panjavi had "stolen the dreams of those she competed against".
Sapstead added: "Zhila Panjavi was one of Britain's leading weightlifting talents, with a bright future ahead of her in the sport. As a result of her own choices, that future has been taken away and Panjavi now faces a lengthy ban from the sport."
The independent National Anti-Doping Panel was not satisfied with Panjavi's explanation for the positive test and she is banned until 7 July 2020.
However, her father and coach Kazem insisted she had not doped and had been made a scapegoat.
"Last year during her holiday in Iran she fell ill and our doctor treated her with medication. We provided the doctor's letter and medication note to Ukad," said Kazem, who himself competed at the 1992 Olympics.
"I feel Ukad want to make an example out of her for others as the findings from the testing do not match and/or consider all the points from her solicitor."
British weightlifting champion Zhila Panjavi has been banned from all sport for four years for taking steroids.