Directors invited representatives from the local business community to join them for a birthday breakfast in their flagship home and electrical store on Friday September 13.
H J Knee's chairman Marcus Holbrow, a family member, said: “To celebrate our 140th birthday is a fantastic achievement.
"It's down to all the staff who have worked for us over the decades, especially those working for us today, and to our loyal customers."
H J Knee downsized from its Trowbridge town centre store to the Spitfire Retail Park in 2014 as part of a response to changes in the retail landscape and the prevailing economic climate.
At the same time Knee's moved from being a store known to ‘sell everything’ to specialising in a simplified range of premium products for the home.
Retail director Ian Vidler said: "Our key product ranges are now large and small kitchen appliances, home furniture and accessories. The other major shift has, of course, been to introduce online purchasing."
The company also owns a store in Malmesbury High Street, a steel fabrication business KAM in Trowbridge and the MAB engineering company in Westbury.