Sgt Mike Friday who works in Hayle and St Ives will start an office job in Camborne in January, but locals said he was "integral" to their community.
He thanked people for their support but said he "always knew" he could be deployed elsewhere.
Devon and Cornwall Police said his "expertise" would be vital to the custody team in Camborne.
Linda Taylor, Mayor of St Ives, said: "They have decided to take a very active, experienced police officer who is very visible to the community and put him into a custody back office role.
"I think this is a really bad decision."
But Ch Insp Mark Eccles from the force said the move was part of "future workforce planning".
He said: "The area will continue to be supported by officers. In the meantime, Sgt Friday will be moving to Camborne where his experience will be vital to the custody team."
Petition organiser Sharon Ciliberto said: "Mike is a role model, a positive influence and an ambassador for the police force.
"He should be awarded an MBE for his role in the community not tuck him away on a custody desk in Camborne police station."
Sgt Friday said he was "deeply touched by the comments and warmth shown towards me by the people of Hayle and St Ives".
He said he was "looking forward to my new challenge in Camborne" and would "always look back fondly on my time here in Hayle".
More than 1,300 people have signed a petition to stop a police sergeant being taken off the beat in Cornwall.