George Campbell Tinning was born in 1910 in Saskatoon, Saskatchewan. He grew up in Winnipeg, Manitoba, and Regina, Saskatchewan taking art classes in Regina until 1938. Later than year he went to study painting at Eliot O'Hara's Watercolour School in Goose Rocks, Maine and at the Art Students' League in New York under Arnold Blanche and William Palmer.
His first exhibition was at Pennsylvania Academy of the Fine Arts in Philadelphia in 1938.
In 1939 he moved to Montréal, where he worked as a graphic artist for Robert Simpson Ltd.
In 1942, he began military service with the Black Watch Royal Highlanders of Canada and served as an official Canadian war artist in Halifax, Sussex, Italy, Belgium, and Holland.
After the war he returned to Montréal and continued his own artistic practice while teaching watercolour painting. He often painted in oil and watercolours most often creating landscape scenes. He also created floral and still life scenes.
From 1950 to 1969, Tinning worked as an illustrator for Ford Motor Company's magazine 'Lincoln-Mercury Times'.
He was the recipient of many commissions, including from the Manoir Hotel and the Montréal Museum of Fine Arts, among others.
Tinning was awarded the Art Association of Montreal's Jessie Dow Prize in 1942, and again in 1948. He became associate of the Royal Canadian Academy of Arts in 1953, a full member in 1970.
Tinning's paintings are part of the collections of the National Gallery of Canada, the National War Museum, the National Archives of Canada, and several other public and private collections.
He died in Montréal in 1996.