Eli Jones, also known as Eli Child, was last seen in the Fixby area of Huddersfield at around 5pm onThursday August 9.
He was reported missing later that night.
He is described as white, 5ft 7in tall, of medium build, with short, light brown hair.
He was last seen wearing a grey t-shirt with black writing on the front, black jogging bottoms and black trainers.
A West Yorkshire Police spokesman, said: "Extensive enquiries have been made since Eli was reported missing but there have so been no further confirmed sightings of him in the Huddersfield area.
"He has links to other areas of the country and it is believed he may have travelled to either the Lincolnshire or Humberside areas."
Anyone who has seen Eli or with information about his movements or current whereabouts is asked to call Kirklees District CID via 101, quoting log 2025 of 08/08.