Alfred Henry Forrester was born in London, the son of a wealthy City lawyer. He began his career as a caricaturist and cartoonist, some of his first caricatures being engraved by George Cruikshank. Alfred's brother, Charles, was a writer and the pair collaborated on illustrated books such as 'Absurdities in Prose and Verse', 1827, and later, 'The Pictorial Grammar' (c.1843).

In the 1830s he worked for the editor John Timbs, contributing images to The Hive and The Mirror, then in the early 1840s he was one of the first to contribute to Punch. Forrester was highly popular at the magazine because of his good humour and jovial nature, as well as being sought after for his skilful illustrations.

Later Forrester turned increasingly to book illustration, with works such as the 'Comic History of the Kings and Queens of England' (c.1850). His illustrations would often have a fantastical element, and he specialised in anthropomorphic animals. He also exhibited at the Royal Academy (1945–6) and his interests were wide ranging, including working on wood and in etching, sculpting figures for production as Parian Ware, and writing short tales, songs and children's stories. He regularly contributed words and images to The Monthly Magazine and Bentley’s Magazine, and images to the Illustrated London News and The Illustrated London Times.

His work can be found in the British Museum, Victoria and Albert Museum and the Houghton Library, Harvard University.