Christopher Crossan was last seen on Netherplace Road, Newton Mearns around 6.45 pm on Sunday, August 5.
He is described as being around 5ft 8, of slim build, with short fair hair.
He was last seen wearing a short sleeved shirt, Rangers shorts and a grey hoodie.
Inspector Iain Greene, Giffnock Police Office, said: “We are appealing for anyone who has seen or heard from Christopher to get in touch with us. He has never went missing before and as time goes on his family are becoming increasingly concerned for his wellbeing.
“Christopher is known to the Newton Mearns and Barrhead area.
“Officers have been checking CCTV and speaking to those who know him to try and trace him.“We urge anyone with information to come forward. We would also appeal to Christopher himself to let us know he is okay.”
Anyone with information should contact Police via 101, quoting incident number 0486 of Sunday 5 August 2018.