Samuel McCall, who is 17 years old, was last in contact with family on Tuesday 26 October 2021.
He is described as white, five feet eight inches tall and of slim build with brown hair that is longer on the top and shorter on the sides.
Inspector Danny Tamblyn, of Dorset Police, said: “We know that Samuel has been in contact with family in recent days, but due to his age we have a duty to find out exactly where he is currently staying and we need to see him in person.
“Officers have been making a number of enquiries to locate him, but these have so far proved unsuccessful. We believe he also has links to the Suffolk and Norfolk areas and may have gone there.
“I would urge anyone with information as to Samuel’s whereabouts, or who sees a teenage boy matching the description given, to please contact Dorset Police.
“Finally, if you see this appeal Samuel please get in touch with us or your family and let us know where exactly you are, as we all just want to make sure that you are safe and well.”
Anyone with information or knowledge as to Samuel’s whereabouts is asked to contact Dorset Police at www.dorset.police.uk, via email firstname.lastname@example.org or by calling 101, quoting occurrence number 55210167722.