Bertram was born in Manly Sydney. Her father, Arthur Moritz Bertram was a wool merchant who established a company in July 1920 to export wool and other produce. A fall in the market in 1922 resulted in a large shipment sold at a loss in the US and he was declared bankrupt in 1925.
Bertram was living in Tamworth in 1928 and contributed drawings to the Sydney Sun 'Sunbeams' supplement, although she was told 'perhaps your drawings were not quite up to the standard' (The Sun 1/7/28). Around this time time, she became a student of the Royal Art Society and studied with Datillo Rubbo (1870–1955). She also worked as a commercial artist.
In late 1930, Moira and sister Kathleen opened the 'smart little' Kurrajong Café in Beardy Street, Armidale. They acquired the business from George Adams Ltd, a well known cake bakery with a chain of franchises across NSW. On new year's eve, a man stole from a display case in the café 'a garlic sausage, valued at 3/6, the property of Kathleen Bertram' (Armidale Express 2/1/1931).
Bertram began creating comics for her own enjoyment. Her fantasy adventure, Jo, debuted in Sydney's Daily Mirror on 8 January 1945. In June 1945, she signed an initial three-month contract with Frank Johnson, with Jo and Her Magic Cape appearing in Frank Johnson Publications until 1946.
KG Murray published Bertram's superhero Flameman in 1946. In 1949, she self-published the four-issue Red Finnegan with her sister Kathleen. Throughout the 1950s, she worked for Horwitz, Invincible and Calvert. She ceased comics work in the late 1950s.
Bertram also painted covers for Horwitz's 'Carter Brown' novels in 1959.