Staff were evacuated while a source told Business Insider the stabbing took place inside their office, which is on the third floor.
Two people suffered stab injuries and one person has been arrested.
Sony Music's offices are in upmarket Kensington, west London, which is the home to several global embassies and a royal residence, Kensington Palace, meaning there is routinely a visible police presence in the area.
One Sony worker, who did not want to be named, told MailOnline: 'We just heard screaming in the canteen. One person was arrested and armed police remain at the scene.
Journalist Simon Neville, who works for the Mail on Sunday newspaper across the street, said he saw workers running from the building and a man in a red jacket being tackled to the ground.
Eyewitness also reported seeing a person armed with a machete at the building. "Several were visibly panicked and some were screaming", according to the Standard.
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Firearms officers descended on Derry Street in central London at about 11am on Friday and were seen outside a building that houses Sony's London headquarters.
A315 Kensington High Street has been closed between Kensington Church Street and Wright's Lane.
'Officers, including firearms officers, and London Ambulance Service are in attendance. Multiple phone calls to the Sony Music offices in Kensington went unanswered.
The incident is "ongoing", the Metropolitan police said. "We took one to hospital and one to a major trauma center".
Reports from the scene claim the incident involved two kitchen staff employed in the building.