In 1779, he purchased a number of spinning mules (also known as Hall i' th' Wood wheels, invented by Samuel Crompton of Bolton) suitable for use in the manufacture of muslin.
By 1781, Oldknow had entered into partnership with his brother, Thomas, and he returned to live at Anderton in 1782, expanding into the manufacture of cotton goods.
The Oldknow brothers' fabrics became favoured in London, where they formed a business agreement with the merchant Samuel Salte;[2] this was the start of his rise to great success.
Oldknow used the putting-out system of production in Anderton near Rivington, whereby raw cotton was distributed to spinners and yarn to weavers who worked in their homes and workshops.
There he purchased a house, warehouse and land on Upper Hillgate from Giles Walmsley;[3] allowing him to increase production at lower costs.
In 1790, mules started to be powered from lineshafts and in the following year Oldknow established his own steam-powered spinning factory at Stockport mills at Hillgate producing 120 count.
[8] In 1787, Oldknow began the purchase of large areas of land at Mellor where the first mill, completed in 1790, created work for 2,000 people.
[9] Oldknow's business greatly depended on his ability to raise credit (much of which was with the Arkwright family) and it was affected when the muslin market fell, partly as a result of the outbreak of hostilities with France.
[9] Oldknow's farming activities allowed him to supply his workers with milk, meat, vegetables and coal and he also built housing for the workforce.
Oldknow used his own system of paper money to pay his workforce which could be exchanged for goods at the village shop or for cash via third parties.
Oldknow was a regular worshipper at the Church of All Saints, Marple and is credited for raising the funds for its restoration and rebuilding work which commenced in 1808 and was completed by 1811, with continued improvements to 1816.
Oldknow's Factory was destroyed by fire in 1892 and although no ground level evidence still exists, there are underground parts of the old mill still present.