Nick Battle, 30, was last seen by his family at 3pm on Thursday, September 30.
Officers have so far been unable to locate or speak with Nick, and extensive searches to find him are ongoing.
Mr Battle is described as white, with short black hair and a beard, and was wearing a black coat and dark grey jogging bottoms.
It is believed he drove south on the A165 towards Hull in his dark blue Mazda car.
Officers said they are extremely concerned for Mr Battle's welfare.
A police spokesperson said: "Anyone who sees Nick, or knows where he is, is asked to contact North Yorkshire Police immediately. Please dial 101, and quote reference NYP-30092021-0325."