Emergency services were called to Birkbeck Road at 6.22am on July 23 after reports of a man being stabbed.
Officers and paramedics from the London Ambulance Service found a man in his 50s with a wound to his arm.
He was treated at the scene before being taken to hospital.
READ MORE:Â LIVE updates as crime scene in place after person stabbed in Sidcup
His injuries are not believed to be life-threatening or life-changing.
The man was later arrested on suspicion of wounding with intent to cause grievous bodily harm and remains in police custody.
A crime scene has been established and several lines of enquiry are ongoing.
