Guy Denning was born in North Somerset in 1965. He has been obsessed with visual art since childhood and started painting in oils at the age of eleven after receiving a set of old paints from a relative that had grown bored with them.

Throughout the 1980s he was repeatedly unsuccessful in his applications to study painting at degree level but continued painting whilst studying art history with the Open University and learning painting technique from older painters he knew in the West of England.

From 1992, he exhibited across Britain. Since 2007 he has also exhibited in the United States of America, Germany, Italy and France. His paintings have been shown in numerous solo and mixed exhibitions. Notable solo shows include 'Purgatorio' at Brooklynite Gallery New York, 'Inferno' at MAGI'900 Bologna and 'Behemoth' at St Martin in the Fields London. His work is held in several public collections, including the Politics Department of Bristol University, the Political Science Department at Galway University and the MAGI'900 Museum of Contemporary Art, Bologna.

He has also been invited to work on a variety of community urban art projects and has developed a distinctive style that builds images from stencilled text. 

In 2011/12 he held a trio of international exhibitions showcasing paintings interpreting Dante's Divine Comedy. The paintings examined Britain's failings and political problems. In 2013 he was one of the artists invited to participate in the Paris Tower 13 urban art project. In 2015 Denning spoke at the UNESCO presentation at the COP21 climate conference concerning artistic activism and climate change awareness.

In 2018, for the centenary of the Armistice, Denning pasted 112 life size drawings of French First World War soldiers to the walls of the village of La Feuillee to mark the loss of that particular village during the war. He lives and works in France.