The member of staff had been working in the Ruthven Ward of the New Craigs Hospital in Inverness before contracting the virus.
Officials from NHS Highland carried out an investigation into use of personal protective equipment (PPE) and clinical risk assessments at the mental health facility before implementing a number of measures to prevent an outbreak.
A small number of people confirmed as close contacts have been requested to isolate as a precaution.
A spokesman for the health board said: “A member of staff employed and working in Ruthven Ward at New Craigs Hospital in Inverness recently tested positive for Covid-19.
“We immediately investigated and initiated standard procedures for monitoring and managing the incident to ensure the safety of patients and staff.
“This has included review and confirmation of appropriate use of PPE and clinical risk assessments of those who have been identified as close contacts of the affected staff member, and as a result a small number of people are self-isolating as a precaution.”
Visiting of patients identified as close contacts to the infected individual NHS have also been restricted.
Speaking to the Press and Journal, Highland MSP Edward Mountain expressed concern over the potential impact on stuffing and levels of care at the hospital.
He said: “I am deeply concerned that the special needs of the people at New Craigs may be affected by this pandemic and I would urge NHS Highland to do all they can to look after the most vulnerable people at New Craigs.”
Local councillor Alex Graham said he was confident NHS Highland could effectively handle the situation.
“I am very sorry to hear this has happened,” he said.
“It’s particularly worrying when it happens within a hospital where there is a significant number of resident patients but I certainly have every confidence NHS Highland will manage that difficult situation very well.
“This acts as a timely reminder to us all to continue to exercise all the precautions advised against Covid-19.”