Patrick Dignan was born in Loughrea, County Galway, Ireland, probably in 1813 or 1814, the son of Peter Dignan and his wife, Margaret Lynch. Nothing is known of his life in Ireland. He emigrated to New South Wales in 1839 and went from there to Auckland, New Zealand, in the Sophia Pate in 1841. Later that year Dignan bought a three-acre cultivation section and in 1842 a town section on a site in Wyndham Street. In 1847 he bought over 300 acres at Point Chevalier. He built a substantial summer-house there in the late 1860s but his principal residence remained in Wyndham Street.
Turning from small farming to hotel-keeping, in 1849 he acquired the licence for the brick-built Clanricarde Hotel in Albert Street. This remained his primary business interest. Later he was also a director of the Auckland Gas Company and a significant shareholder in the Bank of New Zealand. He married Mary Derrom at the Catholic church in Auckland on 23 or 25 July 1846; they were to have 13 sons and a daughter.
Catholics had never been inconsequential in New Zealand. Frederick Weld and Charles Clifford were among the early leaders of the colony while in the Auckland area a number of Irish Catholics soon became prominent in business and public affairs. Dignan was one such. By 1850 he had become a well-known and popular figure, drawing particular support from the Irish military settlers who came to Auckland between 1847 and 1849. He had also laid the basis for a long and busy political career.
In 1851 and 1852 Dignan was elected to the Common Council for the borough of Auckland, from 1853 to 1861 and 1865 to 1876 he served on the Auckland Provincial Council and from 1865 to 1869 he was on the provincial Executive Council. In addition, in 1852 Dignan was on the Gold Reward Committee, in 1853 he joined the committee of the Auckland Mechanics' Institute, and in 1874 he was a member of a committee of inquiry into Mount Eden gaol. He also served on the board of commissioners which preceded the Auckland Harbour Board, and was a trustee of the Auckland Savings Bank.
Dignan served as MHR for City of Auckland West from 1867 to 1870. He spoke in favour of the Native Representation Bill 1867, supporting the representation of Māori in Parliament on the grounds that they were 'natural owners of the soil' and had 'a right to full share of the liberties which we claim for ourselves in this country'. He supported Julius Vogel's public works and immigration schemes of 1870, although he was unwilling to vote for the loans involved without first consulting his constituents. Dignan was one of those who persuaded Sir George Grey to come out of retirement in 1874, and showed himself to be a staunch supporter of Grey in Parliament between 1875 and 1879. He opposed the abolition of the provinces, but otherwise rarely spoke in the House unless it was on parochial issues. He was appointed to the Legislative Council in 1879, a position he retained until his death.
Dignan was one of a number of Irish Catholics who became prominent in business and public affairs in Auckland. As elsewhere in New Zealand, they helped to ensure that Catholicism in New Zealand was never the religion solely of a distinctively poor part of the population, and that it was never without influence. Dignan himself was a member of the committee responsible for building St Patrick's Cathedral; Irish and Catholic functions were often held at 'Dignan's Paddock' in Wyndham Street; he was a part-proprietor of the New Zealand Freeman's Journal; and he was a member of the board of governors of St Peter's school for Catholic boys. Notable among the school's pupils were Dignan's eldest son, Peter, and the future politicians Joseph Tole and John Sheehan. During the early 1870s Peter Dignan practised law in partnership with Sheehan, but subsequently formed the firm of Dignan and Armstrong. He also had a long career in local politics, and was the first New Zealand-born mayor of Auckland (1897–98).
While Patrick Dignan attained relative wealth and social eminence, his career was one of solid rather than spectacular achievement. He was judicious, hard-working, well liked and public-spirited, and not markedly ambitious for wealth or power. He died at New Plymouth on board the Takapuna, returning from Wellington to Auckland, on 20 October 1894. Mary Dignan died on 30 May 1904.
Honoured for his public service, Dignan also endowed his family advantageously. His sons all entered professional employment, while even his later descendants profited from the residential subdivision, begun in 1911, of the land he had bought at Point Chevalier. His name is commemorated there in Dignan Street.