Mellor was born in Ecclesall, Sheffield, where his father was a toolmaker for the Sheffield Twist Drill Company. From the age of eleven, Mellor attended the Junior Art Department of Sheffield College of Art, receiving an intensive training in craft skills. He made his first piece of metalwork – a sweet dish – at this early age. He studied at the Royal College of Art in London from 1950. Mellor's first cutlery, "Pride", designed while he was still a student, is still in production. Mellor also studied at the British School at Rome.
Silversmithing
Returning to Sheffield, Mellor set up a silversmithing workshop-studio making one-off pieces of specially commissioned silverware. His work included a collection of modern silver tableware commissioned by the government for British embassies in a drive to give Britain a more forward-looking image.
Industrial design
Alongside silversmithing Mellor was stimulated by the relatively new design potential of stainless steel. His "Symbol" cutlery, manufactured from 1963 at Walker & Hall's purpose-built modern factory at Bolsover in Derbyshire, was the first high-quality stainless steel cutlery to be produced in quantity in the UK. Mellor was subsequently commissioned by the government to redesign standard issue cutlery for canteens, hospitals, prisons and the railways, reducing the traditional 11-piece place set to five pieces and thereby reducing costs. Mellor worked for the Midlands engineering firm Abacus Municipal on the design of street lighting, bus shelters, public seating and litter bins. Around 140,000 of his bus shelters having been installed since they were first produced in 1959. In 1965 he was commissioned by the Department of the Environment to redesign the national traffic light system as part of an overhaul of traffic signs. Mellor's redesigned traffic lights are still in use.
Manufacturing
In 1973 Mellor made the decision to begin manufacturing his own cutlery designs. To house his factory he renovated a large historic mansion, Broom Hall, in central Sheffield. The building was then derelict. The machines were moved into the extensive Georgian wing. The conversion of the building received a European Architectural Heritage Award. As well as introducing new concepts in cutlery he rethought the traditional methods of production. Workers in the Sheffield cutlery industry had up to then specialised in a single operation, but he introduced a new system whereby his cutlery makers rotate from task to task, increasing job satisfaction through a sense of involvement in the project. In 1990, Mellor finally realised a long-held ambition by commissioning a new purpose-built cutlery factory designed by Michael Hopkins. This factory, known as the Round Building, was built on the circular foundations of the redundant village gas works at Hathersage in the Peak District National Park, 12 miles from Sheffield.
Mellor retired from designing in 2005 at the age of 74. Mellor was married to Fiona MacCarthy, a biographer and cultural historian. They have two children, Corin, product and interior designer, who is Creative Director of David Mellor Design; and Clare, a graphic designer with her own London practice. Mellor died on 7 May 2009 at the age of 78. His wife died in 2020.