Superintendent Adrian Porter, known as Ady, was last seen at his home address in Holt at around 8am on Monday, April 29.
Police and the public are now scouring the area around his home town in a bid to trace him.
Colleagues said the top cop – married dad-of-two – had been having a “difficult time” before his disappearence.
Mr Porter is described as being of slim build with closely shaved hair and 5ft 8in tall.
He is believed to have been wearing a padded jacket, black canvas trousers and a blue hat similar to the one in his photo, and he may have also been wearing glasses.
Police believe he left his home on a light green coloured Genesis bicycle similar to that pictured below.
Simon Bailey, chief constable of Norfolk Police, said: “I’ve known Ady for 30 years, and I speak on behalf of my colleagues in the force when I say that we’re all desperately worried about him.”
He added: “He has now been missing for 24 hours and we are becoming increasingly concerned for his welfare.
“We have got a significant number of additional officers on duty and all our search activities are being coordinated from Holt police station.
“I have asked members of the public who would like to help us with the search to be at Holt police station at 10am and we will coordinate their activities from there.”
Mr Bailey is also appealing to farmers and game keepers to check outbuildings, woods or copses for the bicycle Mr Porter is believed to have left home on.
Inspector Rob Wicks told KLFM: “Ady is not someone who regularly goes missing and he has been having some difficult times of late.We have been offering him lots of support.
“If Ady is out there and sees this – there are lots of friends and colleagues who are concerned about him and will give him any help he needs.
“Ady is a fantastic gentleman and has a heart of gold.
“He has worked for the Constabulary for years with the best interests of the public at the forefront of everything he does.”
Cops are appealing to farmers and game keepers to check outbuildings, woods or copses for the bicycle Mr Porter is believed to have left home on.
Searches took place yesterday and continued on this morning to trace Ady, and his believed to be in the north area of Northfolk.
Police Search Advisors, officers from Norfolk Fire, Norfolk Police’s drone team, and crews from Rescue and Norfolk Lowland Search and Rescue all took part in the hunt.
Anyone who has seen him or knows of his whereabouts should contact Norfolk Police on 101 quoting incident number 275 of 29 April 2019.