Joel McDiarmid was last seen leaving his home address near to the Boghall area of Bathgate around 4pm on Wednesday.
Police say that there have been no further sightings of of the 28 year old, and he has not been in contact with his friends or family.
Officers are becoming increasingly concerned for his welfare.
He has been described as white, 6ft 3ins in height and of slim build with medium-length dyed blond hair.
He was last seen he was wearing a dark green G-Star jacket, black jogging trousers and black trainers.
In a statement on social media, Police Scotland said: “Searches and enquiries are ongoing to trace him.
"We would urge anyone who has seen Joel since Wednesday, or who has any information on his whereabouts, to contact Police Scotland via 101 quoting reference number 1809 of 18 November.”