Welsh mechanical engineer and inventor, born in Montgomeryshire in 1789. Roberts was a quarryman until the age of 20 before beginning work as a pattern maker at Bradley and Horseley ironworks in 1809. After various jobs a cabinet-maker, turner and toolmaker in Liverpool, Manchester and Salford, he moved to London in 1814 to work for Henry Maudslay as a turner and fitter in mariine and machine tool engineering.

Roberts set up his own business in Deansgate, Manchester, in 1816, producing machine tools. The firm moved in 1818 to Pool Fold, and in 1821 to a larger shop in Faulkner Street, with 12-14 mechanics. In 1823, he went into partnership with Thomas Sharp, which lasted until Sharp's death in 1841.

In 1824 he invented his most famous machine, the self-acting spinning mule, and patented it in March 1825. Roberts made extensive use of templates and gauges to standardise production. The mules were made in hundreds, but Roberts gained little financial reward, having spent so much on its development.

In 1832, Roberts patented six separate improvements in steam locomotion, and built the Atlas works to accommodate locomotive manufacture, for which his firm became renowned.

In the early 1820s Roberts helped to establish the Manchester Mechanics' Institute. He joined the Manchester Literary and Philosophical Society in 1823 and was made an honorary member in 1861. He was elected member of the Institution of Civil Engineers in 1838. From 1838 to 1843 he served on the council of the borough of Manchester.

Roberts wound up his business in 1852, becoming a consulting engineer, in Manchester and then in London. He died in poverty on 11 March 1864.