Brian Walker, 67, started work as a sheet metal worker for Oliver Douglas Ltd at Grangefield Industrial Estate in Pudsey when he was 22-years-old in 1973.
Mr Walker moved with the company when it re-located to Amberley Works in Armley in the early 1980s and worked his way up from sheet metal worker to foreman and he will retire from his job as works manager today (Frid March 29).
Oliver Douglas Ltd makes industrial washing machines for the food processing and manufacturing industry.
Father-of-one Mr Walker, of Farsley, said one highlight from his working life was a trip South Africa in 2011 to help with the installation of an industrial washing machine for a company in Cape Town.
Mr Walker said: "I will miss the company, because I have enjoyed working here over the years, and I will miss the people.
"But once I have retired I can do a bit of gardening and some fishing and do a bit more DIY around the house."
Alex Newton, operations manager at Oliver Douglas, said: "Brian has been an invaluable member of Oliver Douglas for many years and has been a key figure in the continued success of the business.
"The high level of his workmanship is visible in hundreds of machines around the world but it is his qualities as works foreman that will be most sorely missed.
"Brian has been an exemplary leader of the team at Amberley Works, carrying out his duties with a level of professionalism that has earned the respect of everyone in the business.
"Although we’re sad to see him go we’d like to wish him a very happy retirement and all the best for the future."
Mr Walker, whose wife Adrienne, 60, works at the Co-op in Farsley, was a pupil at the former boys school on Hough Lane in Bramley and left aged 15 in 1966.
Mr Walker started work as a trainee sheet metal worker at Rodley company George Barkers, which made fridges for shops and industrial use.
After a year he moved to Oldham Signs based at Cross Green Industrial Estate and worked there for six years.
He served his apprenticeship while at Oldham Signs and studied part-time at Kitson College to earn his City and Guilds in sheet metal work.
Mr Walker left Oldham Signs in November 1973 to start work at Oliver Douglas Ltd.