The year 12 student was found injured in Prince Imperial Road, Woolwich at around 4.20pm on January 6.
Emergency services attended and he was initially taken to hospital in a life-threatening condition.
A 19-year old man and 17 year-old girl have been arrested on suspicion of attempted murder and conspiracy to commit murder.
The victim is in stable condition and remains in hospital with non-life threatening and non-life changing injuries.
Both suspects remain in police custody.
The investigation is ongoing.
Shooters Hill College in Red Lion Lane has been closed for two days following the incident.
Parents and carers at the college were informed of the closure, telling them that students will study from home.
A message on the college website reads: “College closed to students. Wednesday 8th January 2025.
“Please see text messages sent to students, parents and carers.
“Students who have exams should arrive as planned as these will still be going ahead.”
A spokesperson for Metropolitan Police said: “A 19-year old man and 17 year-old girl have been arrested on suspicion of attempted murder and conspiracy to commit murder on Tuesday, 7 January following the stabbing of an 18 year-old man at Prince Imperial Road SE18.
“The victim is in stable condition and remains in hospital with non-life threatening and non-life changing injuries.
“Both suspects remain in police custody.
“The investigation is ongoing.
“Anyone with information is asked to call 101 or ‘X’ @MetCC and quote CAD 4354/6Jan.
“You can also provide information anonymously to the independent charity Crimestoppers on 0800 555 111.”
