Reion, 15, went missing on October 8 from his home in Bellingham in Lewisham and has not been seen since.
Police say the teen is known to frequent the south east London areas of Bromley and Beckenham.
Police are urging anyone with information to contact them on 101 quoting the reference 4749/08OCT25.
In a social media post, MPS Lewisham said: “#MISSING | Have you seen Reion, 15 years old, missing from #Bellingham, #Lewisham since 8th October.
“Known to frequent #Beckenham, and #Bromley.
“If seen, please call 101 and quote 4749/08OCT25.”
