Edward McDonald was last seen on Carnbroe Road, around 10am on Monday, November 29.
The 75-year-old is described as 5ft 8” tall, of medium build, with short grey/white hair and a beard.
He was last seen wearing a black jacket, dark khaki fleece, dark trousers, dark shoes and a khaki skip cap.
Edward’s know to visit Glasgow city centre.
He takes regular medication, and it is not known if he has this with him or not.
Police Constable Emma Smith from Motherwell Police Office said: “Edward’s family has not had contact with him since Monday, which is unusual, and they are extremely concerned for him.
“We ask anyone who has seen Edward since Monday, or if Edward himself is reading this, please contact us via 101 quoting incident reference number 3014 of 2 December 21.”