Roger Smith, 70, joined Shropshire Fire and Rescue in 1967 and has been a station commander for the past seven years.
He said he had wanted to continue working, but was forced to step down due to ill health.
Mr Smith completed his final drill in Market Drayton on Tuesday, at the same station he joined 48 years ago.
Shropshire Fire and Rescue said checks had shown him to be the longest-serving current firefighter, but was still some way short of the all-time record.
"I've enjoyed every minute of it," Mr Smith said.
"I've met an awful lot of people and been to thousands of fires and other incidents, too many to remember.
"Every time you go to an incident you don't know what to expect, but you know someone's probably in trouble and you can help.
"There have been a tremendous number of changes over the years, particularly better appliances and equipment.
"Health and safety was virtually non-existent in the 1960s."
The 1989 IRA bombing of Tern Hill Barracks and fires at the defence base on Donnington are among the many incidents he has attended over the years.
A former mayor of Market Drayton, Mr Smith received an award from the county's high sheriff last year to mark his distinguished service to the community and a special celebration is being held on 29 May.
Shropshire Fire and Rescue said the all-time UK record was held by Alfred Thompson from Whitchurch, who joined up as a 16-year-old under the reign of Queen Victoria and served until his death aged 73.
A firefighter, believed to be the longest-serving officer in the UK, has retired after a 48-year career.