Police were called to the robbery on Cambridge Avenue shortly before 4pm on Saturday (August 23).
A 21-year-old man was taken to hospital with a head injury after being assaulted.
His injuries have been deemed not to be life-changing.
He was later arrested on suspicion of possession of an offensive weapon.
There have been no further arrests and police are appealing for more information about the incident.
A Met Police spokesperson said: “Officers were called around 15:50hrs on Saturday, 23 August to a robbery on Cambridge Avenue, Kilburn.
“A 21-year-old man was assaulted and taken to hospital for a head injury.
“His injuries are non-life changing. He was later arrested for possession of an offensive weapon.
“Enquiries remain ongoing and no further arrests have been made.
“Anyone with further information is urged to call 101 referencing 4918/23AUG.”
