James McGibbon was trained as a gardener at Dunrobin Castle, Golspie, in the north-east of Scotland, and at the Royal Botanic Gardens at Kew in 1848. He came to the Cape in 1849 and for a short time worked in the court of the commissioner for the suppression of the slave trade, Cape Town, before finding employment in the garden of William Billingsley. In 1850 he was appointed head gardener (or superintendent) of the Botanic Garden, Cape Town. The garden had been developed for two years by Thomas Draper*, partly with plants from the estate of Baron C.F.H. von Ludwig*. Draper resigned in 1850 and for a short period the garden was in the care of Carl Zeyher*, but in the eyes of its management committee he was too botanically minded and did not bring in enough revenue, hence McGibbon's appointment. Zeyher was retained for a further short period as botanist and collector.
McGibbon's duties included curatorship of the Colonial Herbarium, but he found little time for it and concentrated on cultivating plants and making the Botanic Garden financially viable. He exchanged many plants with institutions in other countries, particularly in England and Australia, sent Cape plants to Kew Gardens (including a Welwitschia in 1864), and forwarded to Kew seeds and plants collected by Dr David Livingstone* and Sir John Kirk* in East Africa. In February 1857 he assisted with the first show of the Cape of Good Hope Horticultural and Floricultural Society by providing plants from the Botanic Garden for display and helping with the prize list and practical arrangements. Years later, in 1874, he presented 64 packets of tree and flower seeds to the newly established Botanic Garden in Pretoria.
In 1858 McGibbon published, at his own expense, a Catalogue of plants in the Botanic Garden, Cape Town. An article by him on "Cultivation of the cotton plant at the Cape" appeared in the South African Agricultural Register in December that same year. Two years later he was appointed vine disease commissioner and after a tour of inspection early in December 1860 compiled a report on The vine disease (Cape Town, 1861). In 1863 he revised the "Gardener's and agricultural calendar" published annually in the Cape of Good Hope almanac.... The next year he issued a Catalogue of fruit-bearing trees and plants in the collection of the Botanic Garden, Cape Town (Cape Town, 1864). At some time in the eighteen-sixties he wrote a short pamphlet on Cultivation of the Camellia japonica at the Cape. He also contributed an article on "The botany of Table Mountain" to The Cape and its people (Cape Town, 1869, pp. 255-263), edited by John Noble*. In this article he pointed out the immense variety of plants growing on the Cape Peninsula and on Table Mountain, with more species than in some European countries. He was an early member of the South African Philosophical Society (founded in 1877) before he retired in 1880 after years of illness. Returning to England he died three years later, survived by his wife Margaret Rennie McGibbon. There are specimens from him in the herbarium at Kew Gardens.