Officers are looking for Reece Chubb who was last seen at 10.45am on Friday, July 17 in Bolton.
Reece is described as 5ft 4in tall with blonde/light brown hair and glasses. He was last seen wearing grey Nike tracksuit bottoms and a black jacket.
A police spokesman said: "We are now concerned for his welfare and are appealing for your help to find Reece. If you have seen him or have any information, please call us on 101 quoting log reference LC-20200717-1564."