The first Australian writer of sensation drama, ahead of George Darrell and Alfred Dampier, Walter H. Cooper worked at a variety of occupations in his short life. He also attempted on several occasions to enter the world of politics, but was unable to gain office. Cooper's early career included a period as journalist with the Queensland Guardian, followed by a position as parliamentary reporter for the Sydney Morning Herald (1866). He joined the Argus for a short period, but returned to the Herald in 1871. During the late 1860s, he also turned his hand to writing for the stage. Arguably his most successful play, the melodrama Colonial Experience, was produced in 1868. Some of the other theatre works Cooper wrote and which were staged during the 1860s and early 1870s include two pantomimes, The History of Kodadad and His Brothers (1866) and Harlequin Little Jack Horner (1868); a farce titled The New Crime; Or, 'Andsome 'Enery's Mare's Nest (1868); the sensation dramas Sun and Shadow (1870), Foiled (1871), and Hazard; Or, Pearce Dyceton's Crime (1872); and the tragedy Rugantino the Ruthless (1872).

Cooper's interest in politics led to his acquaintance with Henry Parkes, and in 1872, he found himself acting as the politician's agent in both the Tamworth and Liverpool Plains electorates. The following year, he was appointed secretary to the Public Charities Commission. Cooper's desire to enter politics was thwarted soon afterwards, however, when his exuberance and forthright opinions put him offside with a number of sitting members. Although dissuaded by Parkes from contesting a seat in East Sydney during the 1874 elections, he nevertheless made a failed attempt in the Lower Hunter region. Despite this setback, Cooper continued to make important contributions to political debates over the next few years through his insightful analyses, published in both newspapers and private pamphlets. In 1874, he travelled to America, hoping to have his plays produced. When this did not eventuate, he returned to Australia and set his sights on entering the legal profession. Supported financially by Parkes, he was admitted to the bar in 1875 but found himself in dire financial straits for sometime afterwards, unable even to repay his benefactor. Not surprisingly, his relationship with Parkes deteriorated as a result. He managed to maintain his political momentum by becoming vice-president of the protectionist Political Reform League and a leading activist in the anti-Chinese agitation movemen. But within a few years, his tangled domestic affairs had begun to impose a strain on both his career and personal judgment.

By 1877, Cooper had managed to pay some of his debts off, but his decision two years later to leave his wife led to a bitter family dispute. At one point, a fight ensued between Cooper and his brother-in-law. The Evening News (15 February 1879, n. pag.) described the scuffle that eventuated, reporting that a gun had been fired. Although Cooper was not injured, the woman with whom he was having an affair was apparently grazed in the arm. Cooper shortly afterwards assaulted John Henniker Heaton, which led to his own arrest and a £10 fine and bond. With his personal situation on a downward spiral, Cooper found himself destitute within a year, and was forced to sell his possessions, including all his books. Writing to Parkes for help, he indicated that his life had been a bitter struggle against adversity, all the more potent 'because my own hand guided its weapons and Poverty, Humiliation and Friendlessness were my companions' (qtd Bede Nairn, Australian Dictionary of Biography, 1969, p.455).

Walter Cooper died shortly afterwards on 26 July 1880 from a combination of heart disease, haemorrhage, and exhaustion. An obituary published in the Sydney Morning Herald two days later suggested that he lacked the personal qualities that would have enabled his undoubted brilliance to shine consistently. Cooper left behind his wife, Ellen, and his six children (five sons and one daughter). One of the last plays to be staged during his life, Fuss; Or, A Tale of the Exhibition, is believed to have been written a year or two previously. Staged at the Victoria Theatre (Sydney) in April 1880, this three-act comedy shows Cooper's insight into human psychology at its best, as he delineates the characteristics of the various nationalities represented at the International Exhibition.