He was born in Ballyshannon, Co. Donegal, Ireland, and was the son of the manager of a local bank who was of English descent. He obtained a post in the custom-house of his native town and held several similar posts in Ireland and England until 1870, when he had retired from the service, and became sub-editor of Fraser's Magazine, which he edited from 1874 to 1879, in succession to James Froude. He had published a volume of Poems in 1850, followed by Day and Night Songs, a volume containing many charming lyrics, in 1855.
Allingham was on terms of close friendship with DG Rossetti, who contributed to the illustration of the Songs. His Letters to Allingham (1854-1870) were edited by Dr. Birkbeck Hill in 1897. Lawrence Bloomfield in Ireland, his most ambitious, though not his most successful work, a narrative poem illustrative of Irish social questions, appeared in 1864. He also edited The Ballad Book for the Golden Treasury series in 1864.
In 1874 Allingham married Helen Paterson, known under her married name as a water-colour painter. He died at Hampstead in 1889, and his ashes are interred at St. Anne's in his native Ballyshannon.
Though working on an unostentatious scale, Allingham produced much excellent lyrical and descriptive poetry, and the best of his pieces are thoroughly national in spirit and local colouring. His verse is clear, fresh, and graceful.
Other works are Fifty Modern Poems (1865), Songs, Poems, and Ballads (1877), Evil May Day (1883), Blackberries (1884), Irish Songs and Poems (1887), and Varieties in Prose (1893), and, arguably his most famous work, "The Faeries" (see below).
William Allingham: a Diary (1907), edited by Mrs Allingham and D Radford, contains many interesting reminiscences of Tennyson, Carlyle and other famous contemporaries.
The Ulster poet John Harold Hewitt felt Allingham's influence keenly, and his attempts to revive his reputation included editing and writing an introduction to The Poems of William Allingham (Oxford University Press/ Dolmen Press, 1967).