Thomas Lamb, 79, has not made contact with his family since he left his home in Almond Road in the Abronhill area on Saturday.
The CCTV footage shows Mr Lamb in Teviot Walk at about 6pm on Saturday evening.
He was seen outside the Carrickstone Bar talking to someone before making his way through the shopping centre and exiting at the old bus station.
Mr Lamb was then seen boarding a Stagecoach X25 bus in Cumbernauld town centre at around 6:10pm before getting off on Moss Road near to Oak Road at 6:23pm.
There is also a further possible sighting of Mr Lamb at around 6:30pm walking along the track at Lime Crescent towards Forrest Road in Abronhill.
Mr Lamb is around 5ft 8in, of slim build with grey hair and walks slowly.
It is believed he was wearing a black anorak, a multi-coloured jumper with a shirt underneath, and blue trousers.
Inspector Philip Maguire from Cumbernauld Police Office said: “Mr Lamb has now been missing for more than two days without making any contact with his family, which is completely out of character.
“He lost his wife very recently and is understandably very upset.
“His family are all very concerned about his well-being and just want to know he is OK.”
Stephen Lamb, 45, Mr Lamb’s son, said: “Dad is very much a homebody who loves spending time with his family. He is elderly and frail and has been very upset since the passing of my mum.
“This is the first time he has ever disappeared for one night, let alone two, and we are all very concerned about him.
“Dad has lived in the community for over 40 years and has a daily routine of walking up to Abronhill town centre for his paper. He is well-known locally and I would ask anyone who may have seen him in the area to please contact Police Scotland on 101.”