Kamau McCallum James, 18, was last seen at the home he shares with his mother in Fartown, Huddersfield, shortly before midnight on August 21.
He has not been seen since or been in contact with his family.
West Yorkshire Police revealed Kamau, who is described as a black male, 5ft 10ins tall, of slim build with black short afro hair and brown eyes, has never gone missing before.
Detective Chief Inspector Fiona Gaffney said: "Before he want missing Kamau was content and happy.
"He had just got his A Level results a few days earlier and had been accepted with an unconditional place at Teeside University.
"This is very out of character for Kamau. He is a shy and introverted young man.
"He has an eye sight condition which means without his glasses he finds it incredibly difficult to see, especially in low light.
"Police and his family are concerned for his welfare and urge him or anyone who has any information or knows his whereabouts to get in touch with police."
Anyone with any information about Kamau's whereabouts is asked to contact the police via 101 quoting log number 2089 of August 25.