Dewhurst Dent said that there were great synergies between the two businesses, which included a long heritage, a luxury customer base and a large export business.
Corgi makes hosiery and knitwear in luxury yarns, with 70% of its business coming via export. Dewhurst Dent, which manufactures gloves, bags, scarves and hats for men and women, sells in department stores including Selfridges, Fenwick, Jarrolds and Palmers and independent retailers.
Corgi's managing director Huw Jones will retire after more than 40 years at the business. However, he will continue as an advisor to the new joint managing directors Chris Jones and Lisa Wood, who are the great great grandchildren of the company's founder Rhys Jones.
Dents, founded in 1777, is now based in Warminster in Wiltshire where it produces its two collections per year. Corgi is based in the Welsh mining village of Ammanford.
The company said in a statement: "The synergy between the twe companies continues in the market place, with a shared retail customer and selling distribution network including a New York showroom. The long history of the two companies and a commitment to creative design and quality will now be utilised to the benefit of both the brands in the UK and also in overseas markets including Russia, Japan, USA, China and Europe."