Most of Osborne’s paintings are figurative and focus on women, children, the elderly, the poor, and the day-to-day life of ordinary people on Dublin streets, as well as series of rural scenes. He also produces city-scapes, which he paints from both sketches and photographs. A prolific artist, he produces oils, watercolours, and numerous pencil sketches. He is best known for his documentary depictions of late 19th century working class life.
Osborne is the second of three sons of William Osborne, a successful animal painter who specialises in portraying horses and dogs for the then prosperous Irish landlords. He is educated at Rathmines School and at the Royal Hibernian Academy school. He learns from his father that there is money to be earned from painting animals. He produces quite a few, including of children with their pets, notably his 1885 A New Arrival, and a series of impressionistic works on cows.
Osborne wins the Taylor Prize in 1881 and 1882, the highest student honour in Ireland of the time, while studying at the Royal Academy of Fine Arts in Antwerp. He is influenced by the Flemish painter Peter Paul Rubens, and the French realist, plein-air painter, Jules Bastien-Lepage, as well as Berthe Morisot.
In 1883, Osborne moves from Antwerp to Brittany where he paints his famous Apple Gathering, Quimperlé, now in the National Gallery of Ireland. Soon after, he moves to England where he works alongside Nathaniel Hill and Augustus Burke at Walberswick. During his period he often returns to Dublin to make preparatory sketches for what becomes his most renowned series, of the everyday lives of the city’s poor. Although highly regarded today, these documentary, street paintings are not commercially successful, and Osborne supplements his income through portrait paintings of the middle class, which are not as artistically satisfying.
In 1886, he is elected to the Royal Hibernian Academy and receives many commissions for portraits. This is an important source of income, as he has no private means of his own. After his sister dies he is involved in looking after her daughter, and his own parents become increasingly financially dependent on him.
In 1892, he returns to Ireland to live in the family residence, and he also keeps a studio at No. 7 St. Stephen’s Green. He spends a considerable amount of time painting outdoors, in Dublin around St. Patrick’s Cathedral or in the country. He is well liked in social circles and counts the surgeon Sir Thornely Stoker, brother of Bram Stoker, among his best friends.
Osborne’s mother becomes ill in the early 1900s, and Walter spends significant periods caring for her. In 1903, while gardening, he overheats himself and catches a chill, which he neglects, and which develops into pneumonia. He dies prematurely from the illness at the age of 43 on April 24, 1903. He is buried in Mount Jerome Cemetery in Dublin.
Some critics have suggested that at the time of his death he is on the brink of his artistic maturity. His final work Tea in the Garden, a fusion of naturalism and impressionism, remains unfinished at his death and is now in the collection of the Hugh Lane Gallery in Dublin. Today his work is highly sought after by collectors.