Siroosh Hussain has been described as “vulnerable” by the Metropolitan Police due to his neurological disorder and autism.
The 34-year-old, who lives in Yorkshire, was visiting London with his family for a funeral.
However he has not been seen since a sighting in Woodhouse Road, North Finchley, on Tuesday (January 7) at 2.14pm.
Siroosh, who is of Pakistani heritage, is described as having fair skin, a beard and black hair.
He is around 5ft 2ins and is of short, stocky build with a mole on the left side of his cheek.
He was thought to be wearing a brown jacket, navy blue jumper, blue shirt, and white and green Puma trainers.
Detective Sergeant Samantha Wilton from the North West Missing Persons Unit said: “We are very worried about the whereabouts of Siroosh who was last seen at 2.14pm on Tuesday (January 7) in Woodhouse Road, North Finchley, N12.
“Siroosh, who lives in Yorkshire, was visiting London with his family for the day for a funeral.
“Siroosh has a neurological disorder and autism. Please get in touch with police as soon as possible if you have any idea where he might be.”
If anyone has seen Siroosh, or has information on his whereabouts, call 101 giving the reference 3759/7DEC or call Crimestoppers anonymously on 0800 555 111.