The Bella Sorella owner was in her shop at the time of the attack, according to an eye witness.
Shop worker Katie Corcoran told The Sun: "It was very frightening. The noise of shattering glass. I've never heard anything like it."
Speculating on the attacker's possible motives, she added: "I don't know if he was showing off or he was doing it to spite Lydia. No-one knows. I just saw him do it then he ran off and everyone went after him."
Georgia chased the man alongside members of a film crew, who made a citizen's arrest and escorted him back to the shop where he was later arrested.
Last night, the boutique's official Twitter feed posted: "Unfortunately today Bella Sorella was vandalised. The suspect is in custody & the issue is being resolved. Open tomorrow as usual x."
A police spokesman said: "An 18-year-old man was arrested for criminal damage and received a caution."
Bright's fellow TOWIE cast member Lauren Goodger faced more serious damage to her salon in February.
Goodger's Lauren Way was petrol bombed by a group of vandals less than 24 hours after it opened.