Two boys, 15, were arrested after a viral video showing a teenage boy lifting up furniture at the shopping centre and chucking it over the barrier on March 1 this year.
The 15kg chair narrowly missed shoppers walking below.
It was part of an internet prank, with the duo previously holding stunts such as “throwing objects off bridges at trains”, the court was told.
A video by one of the boys was played to the court, showing a hooded youth throwing a heavy blue chair over a glass balustrade before they run away swearing in the opposite direction.
The duo who cannot be named for legal reasons, appeared at Stratford Magistrates’ Court on Wednesday (July 16) where the youth who threw the chair admitted criminal damage and recklessly causing a public nuisance.
The teenager who filmed the incident denied the charges.
A previous charge of criminal damage that recklessly endangered life was dropped.
Prosecutor Elizabeth Ajayi said the chair, which was worth £500, was thrown 50ft from the top floor.
One of the boys was seen “lifting a blue sofa and throwing it over the glass balustrade all the way down to the lower floor”, she told the court.
“The video went viral,” she continued.
“It’s fortunate that nobody was injured.”
Both boys admitted their involvement in police interviews, she added.
In a victim impact statement, a Westfield security officer said there had been “unease” among customers since the incident.
The boy who threw the chair told police: “It’s not that deep, it did not hit no-one,” the prosecutor added.
He also told officers he and his co-defendant “regularly indulge” in pranks, including “throwing objects off bridges at trains”, Ms Ajayi said.
District Judge Talwinder Buttar released the youth on conditional bail until sentencing on August 13.
The second boy will next appear on September 24.
