Tyler Proud was last seen at home at 10am on Monday (September 25) and said he was going out.
It is believed he may have travelled to London on the train.
The youngster, who has been living in Crawley but has family in Potters Bar, is white, 5’ 4” and slim.
He was last seen wearing dark jogging bottoms, a grey and black T-shirt and black Kayne West branded trainers.
Anyone who has seen him or knows where he might be is asked to contact police online quoting serial 389 of 25/09.
