Cornish was a member of the "Pitman's Academy" art school at the Spennymoor Settlement in County Durham in North East England. A former miner, he was known for his pictures of mining community life. Other artistic contemporaries of Cornish from the Spennymoor Settlement included Herbert Dees, Robert Heslop and Tom McGuinness. Cornish started work as a miner in 1933, at the age of 14. He continued to work as a miner even after his painting career was established, until he retired as a miner and became a full-time artist in 1966. Cornish was granted an honorary Master of Arts degree by Newcastle University in 1974, and an honorary doctorate by Sunderland University in 2012. He was a contemporary and friend of the artist L. S. Lowry.