He was a landowner’s son and studied art at the Dublin Society. In 1813 he visited London, then worked in Bristol. Danby’s distinctive work began with small panel paintings he produced for his Bristol audience. Danby became the best-known member of the Bristol school of painters but preferred to exhibit more ambitious paintings in London.
When Danby moved to London in 1824 he abandoned naturalistic landscape and contemporary genre subjects to concentrate on painting poetical landscapes in the manner of Claude Lorrain and J.M.W. Turner, and also large biblical scenes.
Danby quarreled with the Royal Academy in 1829, when not elected RA (Constable won by one vote). After his wife left him in 1829 he moved to Switzerland. Between 1831 and 1836 he worked in Geneva, producing chiefly watercolors and topographical paintings. Then he lived in Paris, copying Old Master paintings. He returned to London late in 1838 where re-established his reputation when exhibited privately in Piccadilly, London.
Danby continued to paint poetic fantasy landscapes throughout the 1840s and 1850s, although they became increasingly unfashionable. He also produced landscapes and marine paintings, which derive in color and conception, although not in execution, from those of Turner. These found admirers, although they were too rich in color and imprecise in detail for wide popularity. Danby moved to Exmouth, Devon, in 1847 where he built boats and painted. He was embittered by a life of nearly constant debt and by his failure to gain academic honors.