Mary Konye, 21, faces prison, after she threw concentrated sulphuric acid at Naomi Oni (above) in December 2012.
Konye was caught on CCTV disguised in a full Muslim veil, following Naomi from Victoria’s Secret in Stratford, London, after she finished work.
Konye then doused her with acid in a shocking attack near her home in Dagenham, Essex.
The attack was so severe, 21-year-old Naomi was left with serious burns on her head, neck, arms, legs and body.
She was scarred for life, and required skin graft surgery to cover the burns.
The pair had been friends since secondary school, but reportedly fell out in April 2011 when Miss Oni allegedly accused Konye of texting her boyfriend and called her an 'ugly monster'.
The court then heard that Konye told a friend she planned to have her raped and wanted to disfigure Miss Oni, saying:
‘I’m going to mess up the one thing that girl has – her looks.’
"I’m going to mess up the one thing that girl has – her looks."
Witness Omolola Vincent, 20, told the North-East London court:
‘She said she was going to throw acid on her. She told me she had acid. She bought it online.’
Today the jury at Snaresbrook Crown Court reached its unanimous verdict, with Miss Oni's mother jumped from her set with joy at the guilty ruling.
She will be sentenced on 7 March, and Judge David Radford said:
"I should make clear that, in my judgment, this is a case that will, in all likelihood, need a substantial custodial sentence.
"It is inevitable, but it won't be dealt with until I have received those (pre-sentence) reports."
Baljit Ubhey, Chief Crown Prosecutor in London, who described the attack as "extremely brutal," said:
"Konye has now been brought to justice and must face the full consequences of her appalling actions.
“I would to like praise Naomi's courage and dignity in giving evidence during this trial."
Naomi burst into tears as she left the courtroom and was hugged by family and friends.
On leaving the court, she said she was “glad that a truthful verdict had been reached”.