Walter Pollock was born in London on February 21, 1850, the second son of Sir William Frederick Pollock, 2nd Baronet. His great-grandfather, Mr. David Pollock, was a member of the British royal court and saddler to King George III. One of his grand-uncles, Sir David Pollock, was the chief justice of Bombay, while another, Sir George Pollock, became a field marshal. His own father was an author and Queen's Remembrancer under Queen Victoria from 1874 to 1886, when the post was passed on to his brother George Frederick Pollock who continued to hold the title until the turn of the century. His eldest brother, Sir Frederick Pollock, 3rd Baronet, was a noted lawyer and frequently worked with him during his career.

Educated at Eton and Trinity College, Cambridge, he graduated with a classical degree in 1871 and was called to the bar at the Inner Temple three years later. He developed an interest in literature and history and began lecturing at the Royal Institution, London. Among the subjects he discussed included the works of Richelieu, Colbert, Victor Hugo, Sir Francis Drake and Théophile Gautier. In 1875, he joined the staff of the Saturday Review and became an assistant editor. It was around this time that he began courting Emma Jane Pipon, daughter of Colonel Pipon, Seigneur de Noirmont of Jersey, and the two were married in Chester on January 11, 1876. Their first and only son, Guy Cameron Pollock, was born that same year.

It was while working for the publication that he first began writing professionally and co-wrote Marston: A Story of these Modern Times with Alexander J. Duffield in 1877. He also published literary critical works such as The Modern French Theatre (1878) and Lectures on French Poets (1879), English-language translations of works by Alfred de Musset's and Denis Diderot, and a collection of poetic verses entitled Songs and Rhymes: English and French (1882) and Verses of Two Tongues (1884).

In 1884, Pollock succeeded Philip Harwood as editor of the Saturday Review and remained with the publication for the next 10 years. He became close friends with many members of Victorian Britain's literary circle including Robert Lewis Stevenson, Rudyard Kipling, Oscar Wilde, Egerton Castle, W.E. Henley and Henry Irving. It is also alleged that he had an extramarital affair with English hostess Violet Hunt.

Another close friend and collaborator, Andrew Lang, worked with Pollock on the Saturday Review and published many of Lang's anonymous reviews and "middle" articles. Pollock continued writing, mostly fiction and poetry, and co-authored Uncle Jack (1885) with Sir Walter Besant and He (1887) with Andrew Lang. By himself, he wrote A Nine Men's Morrice (1889), Old and New (1890), The Seal of Fate (1891) and King Zub, and Other Stories (1893). In addition, Pollock contributed 26 poems of "magazine verse" to Longman's from 1890 to 1905. He and Besant also wrote The Ballad-Monger, a stage adaptation of Théodore Faullain de Banville's Gringoire, which was produced by Herbert Beerbohm Tree at the Haymarket Theatre.

In 1894, Pollock left the Saturday Review and went to live at Chawton in Hampshire to devote himself to writing full time. He wrote novels on German student life, at least one book in French, Monsieur le Marquis de -- (1780-1793), Memoires Inédits Recueillis (1894), various plays, and also made several excursions into belles-lettres. A second collaboration with Sir Walter Besant produced The Charm and Other Drawing-Room Plays (1896). The next year, he co-wrote Fencing (1897) as part of the Badminton series with F. C. Grove and Camille Prévost (Pollock then being considered the finest amateur fencer in Britain) as well as King and Artist: A Romantic Play in Five Acts (1897) with Lilian Moubrey.

Two years later, he wrote Jane Austen: Her Contemporaries and Herself (1899), considered one of the most important works of literary criticism on the female author, and published a revised edition of Watts Phillips' The Dead Heart: A Story of the French Revolution (1900). He and his son Guy Cameron Pollock wrote a novel together, Hay Fever (1905), and wrote biographies of two of his friends titled Impressions of Henry Irving (1908) and The Art of the Hon. John Collier (1914). His final book was Icarian Flights (1920). His wife died in 1922; afterwards she was said to have been the inspiration for his poetry. Pollock lived in retirement until his own death on February 21, 1926.