Michael Roberts, 53, who is also known as Mike, was last seen in the early hours of June 4 on North Walk in the Barry area.
He was wearing black trousers with two white stripes and a black hoodie at the time of his disappearance, according to South Wales Police.
Anyone who has seen him or who has information that could help police is asked to contact officers.
A spokesperson for South Wales Police said: “Michael Roberts, 53, also known as Mike, has been reported missing. He was last seen in the early hours of Thursday, 4 June at around 3:30am on North Walk in Barry.
“Mike was wearing black trousers with two white stripes and a black hoody.
“If you have seen Mike or have any information that could help us find him, please get in touch quoting occurrence number 2600174607”.
The public is urged to reference number 2600174607 when contacting police online or by calling 101.
Alternatively, information can also be given via Crimestoppers anonymously on 0800 555 111, or their online form at Give information | Crimestoppers (https://orlo.uk/X49jb.
