John Rigg was born at St Kilda, Melbourne, Australia, on 1 November 1858, the son of Catherine Campbell Leckie and her husband, John Rigg, an accountant. The family emigrated to Dunedin, New Zealand, in 1863 or 1864, before settling in Wellington where Rigg was educated. His strongly Catholic family hoped he would enter the priesthood, but when his father lost his job, John was forced to leave school at the age of 12. He would later describe this experience of poverty and unemployment as his private revolution, which 'found in me the makings of a snob and left me a Socialist.'
Rigg entered the printing trade in 1872 as an apprentice. He was to retain a deep bond to the trade for the rest of his life. He joined the Wellington Typographical Society in 1877, and was involved in its protests against the teaching of trades in gaols and the use of prison labour for printing. In 1887 he came to prominence in union affairs as chairman of a committee opposed to boy labour in printing, which led to the revival of the Wellington Trades and Labour Council in 1888. His activities helped secure the rights of apprentices in printing and allied trades, but cost him his job with the Wellington firm Lyon and Blair. Blacklisted, he left for Melbourne, where he spent two years as a printer and a union delegate.
However, after 1900 Rigg's parliamentary career reflected the gradual alienation of labour from the Liberals. He believed that through the Court of Arbitration it was possible to achieve industrial harmony, particularly if the court's powers were augmented to allow it to recommend profit-sharing, but he was increasingly disillusioned with its administration. In 1904 he helped form the Political Labour League of New Zealand. Heavy electoral defeats for the league's candidates in 1905 again convinced Rigg of the expediency of the Lib–Lab alliance, but his support for government policies was increasingly conditional. He was reappointed to the Legislative Council in 1907 in what the New Zealand Times described as a display of 'quixotic magnanimity' by the government.
Rigg's belief in the right to strike had long caused tension between him and his Liberal colleagues. His rift with the government was deepened by the Industrial Conciliation and Arbitration Amendment Act 1908, which tightened penalties for strikers and outraged many in the union movement. He described the amendment as 'the most tyrannical measure ever introduced into an English-speaking Parliament' and as a declaration of war against workers. His refusal to condemn the 1913 waterfront strike ensured that the Reform government did not reappoint him to the Legislative Council in 1914.
His greatest achievement was helping the diverse labour movement reach an uneasy but lasting accord on organisation and tactics. As chairman, Rigg showed great skill in preventing the unity congresses of 1913 from falling into faction-ridden chaos, particularly by manoeuvring discussion away from the divisive questions of solidarity during strikes, and compulsory military training. The following year he helped organise Labour Representation Committees in Wellington and Dunedin.
He also achieved acclaim through his writing, particularly his highly regarded How to conduct a meeting (1917). He published works advocating currency reform and municipal socialism, which led to his unsuccessful attempt for the Wellington mayoralty in 1909. He edited the Weekly Herald briefly, was involved in a wide range of cultural and sporting organisations, and wrote an uncompleted autobiography combined with a history of the labour movement.
Rigg was a man of moderate political views and unostentatious style, who had worked hard to prevent ideological and personal differences from dividing the developing Labour party. Paradoxically, the confrontational side of his nature led him to become alienated from the movement. His career was marked not only by sporadic clashes with the press (one incident led to an assault charge against the editor of the Christchurch Truth, J. S. Evison), but also by a number of bitter disputes with other labour leaders, such as J. T. Paul. In 1914 he was rejected as a parliamentary candidate by the Labour Representation Committee. He unwisely threatened to form a new pro-Liberal labour party in 1916, and in 1919 his bid to stand as a New Zealand Labour Party candidate failed on a technicality.
Rigg was married twice: in Wellington on 3 June 1908 to Pauline Margaret Isabel Anketell, from whom he was divorced on 20 June 1918; and in Wellington on 16 December 1918 to a divorcée, Louise Eastwood (née De Cleene), with whom he had two children. He drifted from the political scene, and moved to Christchurch around 1920, where he taught elocution and spent much of his time as a tutor for the Workers' Educational Association. In 1937 the first Labour government recognised his pioneering role in their party's development with his appointment as a CMG. He died in Christchurch on 20 October 1943. Louise Rigg died in 1955.