Cotman was born in Norwich, England, on 16 May 1782, the eldest son of a prosperous silk merchant and lace dealer, and was educated at the Norwich School. He showed a talent for art from an early age and would often go out on frequent drawing trips into the surrounding countryside.
In 1800, aged 18, Cotman exhibited at the Royal Academy for the first time, showing five scenes of Surrey and one of Harlech Castle. In 1800 he was awarded an honorary palette by the Society of Arts. He continued to exhibit at the academy until 1806, and went on several extended drawing trips through England and Wales.
While based in London, Cotman had spent some time in the city of his birth, and in September 1802 advertised his services as teacher of drawing in the Norwich Mercury. In 1806 he returned to live in Norwich and joined the “Norwich Society of Artists”, exhibiting 20 works, including six portraits, at the society’s exhibition in 1807
From 1812 to 1823, Cotman lived on the coast at Great Yarmouth where he studied shipping and mastered the form of waves. Some of his finest marine pieces date from this time. He returned to Norwich in 1824, hoping to improve his financial position, and moved into a large house in St Martin’s Plain, opposite the Bishop’s Palace, where he built up a collection of prints, books, armour and many models of ships.
Cotman died in July 1842, and was buried in the cemetery at St. John’s Wood Chapel. All his works and collection of prints and books were sold by auction at Christie’s, realising just over £525 – a relatively paltry sum.