Josiah Nix was born on 12 June 1847 in Oxford, the fifth child and second son of James and Emma Nix, née Carter. James Nix (1810-1873) was a police officer in the Oxford City constabulary, rising to the rank of sergeant. After a period as apprentice to a shoemaker, Josiah established himself in business as a provision merchant. He was also active in local politics, prominent as a volunteer organiser for the Liberals in municipal and parliamentary elections in the 1870s, and he was called to give evidence before the Election Commission in December 1880, following allegations of widespread malpractice by all parties in Oxford in the General Election and subsequent by-election of that year.
The Nix family were stalwarts of the New Inn Hall Street Wesleyan society: Emma Nix (1814-1895) and her eldest son James (1835-1909) were class-leaders, and James was also a Local Preacher, Circuit Chapel Secretary and Circuit Steward, playing a major part in the expansion of Methodism in Oxford in the last quarter of the nineteenth century. The stained-glass rose window in Wesley Memorial church, was given in 1878 in memory of the Nix family.
During the ministry of Hugh Price Hughes Josiah was converted to evangelical Christianity and to temperance. His gifts as an organiser and public speaker were harnessed for Methodist evangelism, first in and around Oxford, and later, at Hughes' invitation, in Brixton Hill, and then in connection with the newly-established West London Mission, where he had particular responsibility for Wardour Hall. He was the first Organising Secretary of the London Mission Band Union, served as a Connexional Gospel Temperance Missioner and then became a Connexional Evangelist.
A broad-shouldered, stocky man with a racy sense of humour, an unconventional style and a commanding voice, Nix relished the cut-and-thrust of open-air preaching, and conducted missions across the Connexion. He founded the Racecourse Mission, and became a familiar figure at Epsom, Ascot and Doncaster. Married and widowed three times, Josiah Nix died in Reeth on 31 March 1924 and was interred in Grinton churchyard.