Lennon Cooper, 15, was last seen at around 4pm on Friday October 22 in Belle Isle.
Police are appealing for information to help locate him.
Lennon is described as white male, 5ft6, slight build with short brown hair and brown eyes.
He was last seen wearing a dark blue Rab puffa coat with an orange logo, dark blue Under Armour tracksuit bottoms, a grey t-shirt and black Nike trainers with reflective strips on.
Lennon has links to the Beeston, Belle Isle and Rothwell, as well as York and North Yorkshire.
Officers are growing increasingly concerned for his welfare and are appealing to the public to assist.
Anyone who has any information as to Lennon’s whereabouts is asked to call police on 101 quoting log 0002 of 23/10.