Thomas Bracken, the son of Margaret Kiernan and her husband, Thomas Bracken, was baptised a Catholic at Clonee, County Meath, Ireland, on 30 December 1841. His mother died in 1846, and his father, a postmaster, died in 1852. Thomas was cared for by an aunt until about the age of 12, when he was sent to Australia to the care of his uncle, John Kiernan, a farmer at Moonee Ponds, near Melbourne. He worked on his uncle's farm for about a year, and was then apprenticed to a chemist in Bendigo. After about 18 months he went to work on a station at Colbinabbin, north-east of Bendigo, where he became a proficient horseman and shearer. Little is known of this period of Bracken's life, except that he began writing verse during these years and published a volume, The haunted vale, in 1867.
Bracken is thought to have arrived in Dunedin, New Zealand, in early 1869. He may have been employed briefly as a warder at the Dunedin gaol, but he soon moved to journalism, finding employment on the Otago Guardian. Together with John and Alexander Bathgate he founded a threepenny weekly newspaper, the Saturday Advertiser, Time-table, and New Zealand Literary Miscellany, the first issue of which appeared on 17 July 1875. The paper was immediately successful under Bracken's editorship, attaining a circulation of about 7,000. It attracted informed contributors and stimulated discussion of political, literary and social issues. By 1879 it was being issued as the weekly edition of the Morning Herald, and in 1880 its title became the New Zealand Public Opinion, Sportsman and Saturday Advertiser.
On 1 February 1883, at St John's Church in Roslyn, Dunedin, Thomas Bracken married Helen Hester Copley, the daughter of a barrister. A son, Charles Copley, was born on 17 August 1885. By this time Bracken had ended his association with the Advertiser. In the early 1880s he held an editorial position with the Morning Herald, but resigned when the paper attacked Robert Stout. In 1885, together with John Bathgate and others, he became a part-owner of the paper, now called the Evening Herald. He retained this business interest until the paper was sold in September 1890.
In 1879 Bracken stood unsuccessfully for Parliament for the City of Dunedin. His entry into politics was prompted by his support for George Grey and his acquaintance with Robert Stout, as well as his strong concern for the underprivileged. In 1881 he won the seat of Dunedin Central, and was in Parliament for three years. His first speech, on 26 May 1882, was a forceful criticism of the native minister, John Bryce, and the West Coast Peace Preservation Bill: Bracken attacked the government's dealings with the Parihaka Māori, the detention of Te Whiti and Tohu, and what he saw as a dishonourable breaching of the commitments of the Treaty of Waitangi. Throughout the session he made conscientious contributions on local matters, taking a particular interest in prison policy and speaking on education and Catholic schools, the Land Bill, and the Eight Hours Bill, which he seconded for a second reading. An anecdote tells of his breaking into song and leading the House in a chorus of 'Behave yoursel before folk' during a vigorous debate on the Gaming and Lotteries Bill.
In late 1883 Bracken travelled to Samoa with John Lundon, representative there for the Auckland South Sea Island Produce Company, and was an advocate of a New Zealand policy of annexation. In the general election of the following year he was defeated by just three votes by J. B. B. Bradshaw, in spite of support from the Otago Trades and Labour Council and the constitutional reform movement. After Bradshaw's death in 1886 he was returned to the House in a by-election. A committed Irish nationalist, he gave an impassioned speech urging support for William Gladstone's opposition to the Imperial Parliament's crimes bill which contained measures Bracken described as 'government coercion in Ireland'. He also spoke briefly against Julius Vogel's Women's Suffrage Bill. The parliamentary session lasted for less than seven weeks, and Bracken did not seek re-election after the dissolution.
Journalism and poetry seem always to have been as important to Bracken as politics. From his arrival in Dunedin he continued the verse writing he had begun in Victoria, and he published prolifically in New Zealand and Australia and occasionally in England. The title page of his first New Zealand collection, Behind the tomb (1871), refers to his authorship of the Otago Caledonian Society's prize poems for 1869 and 1871. He used the pseudonym 'Paddy Murphy' as well as his own name, and quickly gained wide popularity, which was confirmed with his next major volume, Flowers of the free lands (1877). He drew to his support the Presbyterian minister and social reformer Rutherford Waddell, who wrote an introduction to Bracken's 1884 collection, Lays of the land of the Māori and moa, and Robert Stout, who contributed a long 'historical sketch' to accompany George Grey's briefer preface to Musings in Māoriland (1890). As a prolific poet and also a generous editor, Bracken contributed to satisfying a popular wish that an indigenous literature of some value might be emerging as the colony celebrated its first 50 years. Stout wrote of him as 'one whose country is Australasia, for he has been reared in Victoria and New Zealand. He is helping, and has helped, to create a national literature'.
Bracken's last major book was a selection from his previous volumes, entitled Lays and lyrics: God's own country and other poems (1893). He also published two issues of a literary periodical, Tom Bracken's Annual, in 1896 and 1897; a book of essay sketches of Dunedin clergymen, Pulpit pictures (1876), over the pseudonym 'Didymus'; a collection of reminiscences of his life in Victoria, Dear old Bendigo (1892); and miscellaneous pamphlets and compilations. His single most important literary achievement, however, was his poem 'God defend New Zealand'. On 1 July 1876 the New Zealand Saturday Advertiser published the five stanzas under the title 'National hymn', and announced a competition to compose an air for the poem for a prize of 10 guineas. The 12 entries were judged by a panel of three German musicians in Melbourne, who unanimously chose the score written over the pseudonym 'Orpheus' by John Joseph Woods, a teacher from Lawrence in Otago. The first performance of the music may have been an arrangement for the Dunedin Royal Artillery Band, which the band planned to perform in a street parade in December 1876. The first presentation of the poem with its music was on Christmas night 1876, at a concert in the Queen's Theatre by the Lydia Howarde troupe.
On 17 September 1877 Bracken relinquished the copyright of the poem to Woods, who undertook the publishing and promotion of an edition of the work. It was printed in London in 1878, and a Māori translation by T. H. Smith, recently retired judge of the Native Land Court, was supplied to Woods by George Grey. Bracken had earlier included the text of the poem in Flowers of the free lands.
'God defend New Zealand' rapidly gained popular, although not official, recognition. At Woods's request, Richard Seddon presented a copy to Queen Victoria at her diamond jubilee, and at the outbreak of the First World War Woods assigned the copyright to the publishers Charles Begg and Company. In the 1930s the urgings of James McDermott, chief engineer in the Post and Telegraph Department, were instrumental in gaining official adoption of the work. The National Centennial Council recommended in December 1938 that the government adopt 'God defend New Zealand' as the national hymn, and on 1 May 1940 the minister of internal affairs, W. E. Parry, announced the government's purchase of the rights to Bracken's words and Woods's music. However, the work was not given equal status with 'God save the Queen' as a national anthem until 1977.
Bracken had been born into a Catholic family but lapsed in the faith, and was for many years a freethinker and a Mason. He was opposed to the introduction of religious teaching into state schools, and he saw Catholic opposition to secular education as ill advised. Nevertheless, his continued sympathetic association with the Catholic church went back at least to 1874, when R. A. Loughnan, one of the founding directors of the New Zealand Tablet, employed him to canvass for shares in the paper. The composition in 1879 of the poem 'Not understood' has been attributed to Bracken's unsuccessful application to Bishop Patrick Moran for appointment as editor of the Tablet.
From 1890 at least, there is some suggestion of continuing financial difficulty in Bracken's affairs. The expensive de luxe edition of Musings in Māoriland did not sell well in Australia, and economic problems appear to have been accentuated by a promotional tour of that country. The Evening Herald was sold at this time, and by 1892 Bracken was apparently in considerable financial distress. Seddon offered him a clerical post in the Land and Income Tax Department, but he chose instead to accept a position as a reader and record clerk of the House in May 1894. In late 1895 ill health forced him to resign. He returned to Dunedin, and died there of goitre on the night of 16 February 1898, survived by his wife and 12-year-old son. Helen Bracken died in the Orokonui Home, where she was a patient for the last 10 years of her life, on 26 November 1920.
Bracken's poetry was highly praised in his lifetime and in the early twentieth century. He and Alfred Domett were the only New Zealand poets mentioned in the 1916 Cambridge history of English literature. A posthumous collection, Not understood and other poems, went to eight printings between 1905 and 1928 and at least four reprintings between 1942 and 1956, its title poem gaining worldwide popularity. However, although a selection, Ballads, was published in 1975, recent literary historians and anthologists have shown little interest in him, and he did not appear in major anthologies of New Zealand poetry published in 1956, 1960 and 1985. His current poetic reputation must depend, therefore, solely on 'God defend New Zealand'. It may be that this recognition owes little to reasoned response to Bracken's words and much more to the readily identifiable melody by Woods. The poem remains, nevertheless, Bracken's one permanent poetic memorial.