Prudence Heward was born Efa Prudence Heward in Montréal, Quebec, Canada into a very well off family and was educated at private schools throughout her childhood. She showed an interest in art at a young age and was encouraged by her family to pursue her interests. She eventually attended the Art Association of Montreal.

During the First World War, after her brothers joined the Canadian Army to fight overseas, Heward enlisted as a volunteer with the Red Cross and moved to England. After the war ended she returned to Canada where she continued to paint and joined a painting group from Montréal called the Beaver Hall Hill Group. In 1924 she had her first public showing in Toronto at the Royal Canadian Academy of Arts. At this time however, it was still an era when women artists were given little credibility so it wasn't until eight years later, in 1932, that Heward had her first solo exhibition in her native Montréal at the Scott Gallery.

She was soon invited to exhibit with the Group of Seven and through it became friends with A.Y. Jackson with whom she would go on sketching excursions along the Saint Lawrence River. While she did a number of landscapes, with a particular attachment for Quebec's Eastern Townships, Heward is most recognized for her portraits, which provide compelling representations of women and children.

In 1933, Prudence Heward co-founded the Canadian Group of Painters, but her life-long struggle with asthma and other health problems eventually slowed her down. A 1939 car accident curtailed her abilities even further though she still produced some outstanding portraits until 1945 when her health had deteriorated to the point where she had to give up painting.

She passed away two years later, while seeking medical treatment in Los Angeles, California.