Henry Walton was baptised at Tivetshall St Mary, Norfolk, on 5 January 1746, second of three children of Samuel Walton (1710-1797), a wealthy farmer and his wife Ann, née Newstead (1711-1797) of Dickleburgh. In 1765, aged 19, Walton moved to London, although apparently not with the intention of becoming an artist as he had a private income and had no need to earn a living by painting. But in 1770 he began studying art at the Maiden Lane Academy in Covent Garden, London, about which time he became a pupil of Johann Zoffany (1733-1810). In 1771, Walton was living at Great Chandos Street, Covent Garden, painting portraits in oil and miniatures, often featuring close friends and family. About this time he took an apprentice, the miniature painter Edward Miles (1752–1828), of Great Yarmouth, Norfolk who remained with him until 1794.

In 1771 Walton was elected a fellow of the Society of Artists, where he exhibited two portraits and in 1772 elected a director of the society, showing four works at that year’s exhibition. He married at Wortham, Suffolk, on 10 September 1771 Elizabeth, second daughter of the ten children of Robert Rust, a draper of Wortham, Suffolk and his wife Elizabeth, daughter of John Russell of Otley, Suffolk. They had no children. Shortly after the marriage Walton purchased Oak Tree Farm, in the village of Burgate, near Wortham, where he converted one of the cottages into a house and studio. There Walton painted landscapes, although these remain unidentified, and during the early to mid-1770s Walton seems to have worked principally as a portrait painter, among his most celebrated sitters being Edward Gibbon (1737-1794), whom he painted on no fewer than six occasions. Other prominent sitters included the Revd William Gilpin, Horatio Walpole, first earl of Orford, and Lord Cornwallis. All these portraits were engraved during the artist’s lifetime, the print after Lord Cornwallis reputedly hanging in virtually every household in Suffolk. At some time during 1773-74 Walton reputably travelled to Paris, making the acquaintance of the French artist Jean-Baptiste Siméon Chardin (1699-1779). According to his Great Yarmouth friend Dawson Turner (1775-1858), Walton frequently went there ‘with a view of studying or of buying pictures’. In November 1778 Walton was turned down for membership of the Royal Academy and showed only two more works there in 1779, after which he ceased to exhibit altogether and during the 1780s, Walton devoted himself increasingly to his farm in Burgate. Among his more significant portraits and conversation pieces of his later period are William Crowfoot and the Burroughes Brothers Boating on the River Waveney (c.1780), Sir Bellingham Graham, 5th Bt. and his children (c.1785), and Sir Robert Buxton and Lady Buxton with their daughter Anne (1786). He also travelled to Yorkshire where he painted portraits of important local families. In 1784 he was living in Half Moon Street, London and in 1790 in Curzon Street as an established picture dealer and adviser to some major private collectors, notably Lord Lansdowne, Lord Fitzwilliam, and Sir Thomas Beauchamp-Proctor, to whom he sold a Poussin from the collection of Sir Joshua Reynolds. Walton’s expertise was apparently such that ‘there was scarcely a picture of note in this country, with the history of which he was unacquainted’.

Walton continued to paint local Norfolk and Suffolk families well into the early 1800s, among his last works being an unfinished portrait of John Trew, an old servant of his friends the Frere family, painted in 1810. By now Walton was in poor health having contracted a fever ‘which caused a great alteration in his appearance’. One evening in May 1813, on returning from a party to his London lodgings at Mrs. Fraser’s in New Bond Street, Walton complained of feeling unwell. He was found dead in bed the next morning, the immediate cause of death being described as hydrothorax and pleurisy. Walton was buried near his parents in St Mary’s churchyard at Brome, Suffolk and his tomb is inscribed ‘Henry Walton, gent. 19 May 1813, aged 66’.