Amrit Lalji, who worked for Compass Group's Eurest division at Terminal One, was sacked last month for insisting she had to wear the stud as part of her Hindu religion.
She appealed against her sacking with the help of the GMB union and after an internal hearing, Eurest has agreed to reinstate her. It admitted that the sacking had been due to a "misunderstanding" of staff rules.
As Lalji works in customer services, Eurest's mandatory rules relating to catering staff wearing facial piercings did not apply, a spokesman said.
"Since Mrs Lalji is not engaged in catering, her dismissal resulted from a misunderstanding of the rules and is therefore unjustified," he said.
GMB organiser Tahir Bhatti added: "We welcome Eurest's decision that she is reinstated in her position immediate and without detriment or loss of pay."
By Daniel Thomas
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