Ansdell is believed to have studied with W.C. Smith, a portrait painter in Chatham, England, around the age of twenty. When Ansdell was twenty-one he returned to Liverpool and studied at the Royal Academy there, at the same time establishing a studio. He married in 1841. The Ansdells remained in Liverpool until 1847, when they moved to Kensington, a section of London. After a series of trips to Spain in the late 1850s, during which he collaborated with John Phillip, Ansdell began spending a great deal of time in Scotland. Much of his work features sporting dogs, although he painted a wide variety of animals, mostly domestic; his subjects included shepherds with their sheep, horses, gamekeepers with dead game, coursing and angling. Besides John Phillip, he collaborated with W.P. Frith, Thomas Creswick, and others. Some of his patrons included the Earls of Derby, Sefton, and Spencer, as well as, the Marquess of Bute.
Ansdell served as President of the Liverpool Academy in 1845. He was also a member of the Royal Academy in London. He received a third-class medal at the Paris Salon in 1855. He exhibited numerous works at the Royal Academy beginning in 1840, among them Fox Hunting in the North in 1845, Highland Shepherd in 1856, Stag at Bay in 1869, and Hunting the Boar in 1883. It is believed that he exhibited 149 works at the Royal Academy over the course of his career. He also exhibited at the Royal British Institute. His work is held by several institutions in Britain, among them the Merseyside County Council Walker Art Gallery, the Fylde Borough Council, and the Harris Museum and Art Gallery in Preston. In 1844 he painted a work titled Caledonian Coursing Meeting at Ardoss, Ayrshire, Scotland, and in 1969 it sold for 34,000 guineas, which was then a record-setting price for a piece of his work.