The 20-year-old high flying Exeter university student, from Orpington, Kent, claimed that she had been forced to drive a drug dealer and his friends around during the mass disturbances in London.
But, after seeing photos taken by witnesses of her laughing and joking at the wheel of her car, the jury decided that she was a willing participant in the crime spree.
In a partial verdict they found her guilty of burglary from a Comet Store in Greenwich, south east London on August 9, the worst night of the summer rioting.
It was there at around 2am that she was arrested at the wheel of her Smart Car with more than £5,000 worth of electrical goods in the back.
Johnson, who looked stunned as the verdict was read out, was said by the arresting officer to have revved the engine of the car and he was forced to smash the window to grab the keys.
The jury, who deliberated for nine hours, found her not guilty of burglary at a Curry's store in Charlton, south east London.
The jury are continuing to deliberate on a third count of handling stolen goods.
Her co-defendant, a 17-year-old business studies student who cannot be named, was also found guilty of the burglary at Comet.
He had already pleaded guilty to burglary of cigarettes and alcohol from a BP garage during the crime spree.
The jury had heard how Johnson had set out early in the evening to deliver a phone charger to her friend, Emmanuel Okubote, 20, a convicted crack cocaine dealer and thief, otherwise known as T-Man.
When she arrived at their meeting point in Catford, south London, he jumped into the passenger seat while others climbed into the back of the car, prosecutors said.
Johnson told detectives she was instructed to drive from one place to another late at night and into the early hours of the morning.
When she stopped, her passengers - most of whom she claimed never to have met before - would embark on a looting mission.
The court heard that Johnson, who previously tried to kill herself, began a close friendship with Okubote during the summer after being introduced to him by a friend she met while a mental health unit outpatient.
She told the court she was ordered to act as his driver on August 8 and was too frightened to flee.
Asked why she had not refused to drive that night, she told police: "I didn't get the impression they were the sort of people you say no to... I suppose there's a fear of them, there's a general knowledge that these are just not the kind of people who you don't go along with, especially when they are sat in your car and have an idea of your family or registration plate."