He began his working life in the office of a West India merchant in the City of London, who went out of business soon afterwards.

[1] In 1824 he showed portraits of his father and of Alfred Bunn the manager of Drury Lane Theatre at the Royal Academy.

He continued to paint theatrical portraits for some years although what the Dictionary of National Biography calls "pictures of a more fanciful character" came to dominate his production.

[2] From around 1840 he concentrated on portraiture again,[1] depicting both individuals, such as the Duke of Wellington for the London City Club, the Duke of Cambridge for Christ's Hospital, and Sir George Burrows for Saint Bartholomew's Hospital,[2] and large groups, as in his Waterloo Banquet (1842) and Peninsular Heroes (1848).

[1] Knight died at 24 Maida Hill West, London, on 26 March 1881, and was buried in Kensal Green Cemetery.