Police were called to a fight on Leyton High Road at around 8pm on November 11.
Officers arrived with paramedics who treated a 23-year-old man for a stab wound at the scene.
His injuries are not life-threatening or changing.
He was then arrested on suspicion of causing grievous bodily harm and possession of an offensive weapon.
He is in police custody and a crime scene was put in place.
The victim of the alleged assault, a 23-year-old man, left the scene before officers arrived but was later found without any injuries.
A 50-year-old man intervened in the situation and received a hand injury.
Enquiries are ongoing and officers are appealing for information from the public.
A Met Police spokesperson said: “At around 20:00 hrs on Tuesday, 11 November, police were called to reports of an altercation on Leyton High Road, E15.
“Officers attended with the London Ambulance Service, who treated a 23-year-old man for a stab wound at the scene, where his injuries were not life-threatening or life-changing.
“The man was subsequently arrested on suspicion of causing grievous bodily harm and possession of an offensive weapon. He remains in police custody.
“A 50-year-old man who intervened sustained a minor hand injury but did not require hospital treatment.
“The victim of the alleged assault – a 23-year-old man, left the scene before officers arrived but has since been located without any injuries.
“Enquiries are ongoing, and Anyone with information is asked to call 101 or report online, quoting reference 7064/11NOV25.”
