Mountain rescues teams and a coastguard helicopter so far been involved in an "extensive search" for Neil Gillingham, from Kilmarnock, who has not been seen since about 1.30pm on Sunday, March 6, when he was near the the summit of Stob Coire nam Beith.
The 43-year-old, who was walking with his black and white springer spaniel dog had set out to take a route from the Hidden Valley car park to Bidean nam Bian and Stob Coire nam Beith before descending to the Lost Valley.
Police have confirmed that the dog was found safe and well on Monday, however there have been no sightings of Mr Gillingham.
Searches have taked place in the area with members of the Glencoe, Lochaber, Oban, RAF and Police Scotland mountain rescue teams all involved, as well as the HM Coastguard helicopter.
Sergeant Leigh Brown, of Fort William Police Station, said: "Neil did not return as planned from a walk in Glencoe and extensive search activity is now ongoing to locate him.
"I would urge anyone who believes they may have seen or spoken to him at any time since he was last seen near the top of Stob Coire nam Beith on Sunday afternoon to get in touch urgently.
Mr Gillingham is described as being 5ft 8in tall, of stocky build with receding fair hair and blue eyes.
He was wearing a blue Rab waterproof jacket, black thermal trousers and brown walking boots.
Officers have confirmed that the search will continue as soon as conditions are safe for mountain rescue.