Isaac Mason Hill was born in Birmingham, England, on 28 December probably in 1815 or 1816, the son of James Hill and his wife, Deborah Mason. He was educated at a Quaker school and worked as a machine fitter before sailing for Nelson, New Zealand, on 26 September 1841 in the Fifeshire, having paid his own passage. On arrival in Nelson on 1 February 1842, he camped with three of his fellow passengers, Alfred Saunders, John Sylvanus Cotterell and Cyrus Goulter. Hill was appointed cook, but on the first Saturday following their arrival nearly poisoned himself and his companions with a pudding made of tutu berries. Hill's first employment in Nelson was probably as a carpenter, and he soon expressed his support for the rights of labourers in the settlement. On 6 May 1842 he spoke at a meeting of journeymen carpenters, chaired by Richard King, at which it was unanimously resolved that no carpenter should work for less than 12s. per day.
When William Fox was appointed the New Zealand Company's resident agent in Nelson in September 1843 he engaged Hill as a servant. Hill lived in William and Sarah Fox's house overlooking Nelson Haven. Probably in 1844 or 1845 he married Mary Avery in Nelson. They had twelve children, two of whom died in infancy. Isaac and Mary Hill lived in Haven Road. In the 1845 census Isaac was described as a cow-keeper.
In 1847, after a visit to Sydney, Isaac Hill reported that conditions for labourers were on balance no better there than in Nelson, and the moral climate of Nelson was certainly preferable. By 1849 he was a storekeeper in Nelson. He was prominent among the mechanics and labourers who petitioned the New Zealand Company in 1850 for compensation for breach of contract over the harsh and disappointing conditions experienced in Nelson by the early arrivals.
By 1855 Hill had set himself up in business as an ironmonger. His premises were in Waimea Street (Rutherford Street), where he had a shop and a dwelling of four rooms. He remained there with his wife and family until his death on 31 August 1885.
Throughout his life Hill remained a staunch member of the Society of Friends (Quakers). Frederick Tuckett, Samuel Strong, Samuel Stephens, John Sylvanus Cotterell and Hill had formed a closely knit group of the Society of Friends in Nelson. In 1853 two Friends from Yorkshire, Robert Lindsay and Frederick Mackie, arrived in Nelson in the course of an Australasian tour. They purchased Cotterell's town acre and converted the dwelling on the section into a meeting house. It opened for public worship on 15 May 1853, the first meeting house of the Society of Friends in New Zealand.
Hill maintained a strong interest in education, both religious and secular. In March 1842 he was appointed secretary of a committee to collect subscriptions for the erection of a chapel and Sabbath school on a site in Tasman Street, Nelson, leased to them by Captain Arthur Wakefield. This was the first step in the organisation of the Nelson School Society, which was to be an influential model for the national system of primary education in New Zealand.
Isaac Hill was a supporter of J. P. Robinson, the Nelson superintendent, and of his successor, Alfred Saunders. Like Saunders he was a teetotaller, and was a founding member of the Nelson Total Abstinence Society. He was one of the first directors of the Permanent Building Society established in Nelson in 1862.
Hill was the last survivor of a group of Quakers who made a significant impact on the social and religious life of Nelson. On 3 September 1885 the funeral of 'good old Isaac Hill' drew a large procession. He was greatly mourned for his unobtrusive philanthropy and the Colonist reminded Nelson citizens of 'his support of the working man's rights in Nelson,…when the rights of labor in Nelson were something more than a name'.