Josiah Martin was born in London, England, on 1 August 1843, the son of Charlotte Bromley and her husband, Josiah Martin. His father was a melter, and later an actuary. The young Josiah's first job appears to have been in an insurance office. He was in business as a coal merchant when, in London on 24 March 1864, he married Caroline Mary Wakefield. They emigrated to New Zealand a few years later with an infant daughter. After a period farming and running a school at Maungaturoto, Josiah Martin settled with his family in Auckland, where he was involved with the Royal Insurance Company.
In 1874 Martin founded a private academy, later to become Grafton District School, where he was headmaster until 1874. He was a gifted and innovative teacher. In January 1875 he opened the Auckland Model Training School in the Choral Hall in Symonds Street, in which he was shortly after joined by the Reverend E. Browne. Based on similar schools in Germany, Britain and Australia, it aimed to provide a practical and technical course of instruction to students, and practical training for pupil-teachers. It was the first model training school in Auckland.
Martin was also a founding member of the committee of the Auckland School Teachers' Association, formed in June 1873. This group worked towards educational reform and a comprehensive scheme of national education. But his school and his other educational interests were superseded by the introduction of a national system of education in 1877. This event coincided with failing health which compelled him to resign his headmastership in 1879.
Martin now concentrated principally on photography. During 1879 he toured England and Europe, and while in London visited the Royal College of Chemistry, where he made a study of the latest improvements in rapid 'instantaneous' photography using the new gelatin bromide process. On his return to Auckland he opened a photographic business with a studio on the corner of Queen and Grey streets in partnership with W. H. T. Partington, employing the new dry-plate process. After the partnership was dissolved he opened another studio in Edson's building, Queen Street. Martin later sold the portrait business to Charles Hemus and transferred his premises to Victoria Arcade. He favoured topographical and ethnological subjects. As well as selling prints he exploited the market for lantern slides and stereographs.
In an address to the Auckland Photographic Club in May 1890 Martin recalled his early experiences with wet-plate photography when he visited the thermal regions of Tarawera and Rotomahana in 1876. He was to visit the area many times and was there on the eve of the eruption of Mt Tarawera in 1886; some of the photographs he took after the eruption were reproduced by photolithography in the Auckland Evening Star. In 1894, when he offered a selection of 60 New Zealand photographs of ethnological subjects to the Pitt Rivers Museum at Oxford University, he also offered to supply similar photographs of Fiji, Samoa and other Pacific islands. He appears to have visited the islands in 1898, and in 1901 travelled there with S. Percy Smith. He published an account of this trip in Sharland's New Zealand Photographer and also contributed articles and photographs to the Auckland Weekly News and the New Zealand Illustrated Magazine.
Martin gained an international reputation for his ethnological and topographical photographs. His work was exhibited in London at the Colonial and Indian Exhibition of 1886 and he won a gold medal at the Exposition coloniale in Paris in 1889. His photographs are held in the art collections of many major institutions around the world.
Always willing to share his knowledge, he was editor of Sharland's New Zealand Photographer for several years. He was a member of the Auckland Photographic Club and a foundation member and twice secretary of the Auckland Society of Arts. He lectured frequently, not only on photography but also on scientific subjects. Intensely interested in many aspects of science, particularly physics and geology, he was a fellow of the Geological Society of London. His most important lecture, 'The terraces of Rotomahana, New Zealand', was delivered to the society in London on 9 February 1887. Martin was a member of the Auckland Institute for 40 years, serving on its council from 1881 to 1892 and as president in 1889, and regularly spoke to members on both scientific and popular topics. He was also a frequent speaker at the YMCA and delivered a series of popular lectures on physics under the auspices of the Park Road Mutual Improvement Association.
Josiah Martin died on 29 September 1916 at his home in Northcote, Auckland, aged 73. He was survived by three daughters, his wife having predeceased him. In 1958 his daughters presented his collection of negatives to the Auckland Institute and Museum. His photographs provide a record of changed landscapes and societies. Martin was one of the first photographers to realise the commercial potential of photography to encourage tourism, but he was also aware of the need for conservation of the landscape and of the role of photography in providing a documentary record. Above all else he gave leadership and guidance to the developing photographic profession in New Zealand.