When she finished her studies, she taught, painted portraits and created stage designs for Sadler's Wells Theatre.

During the Second World War, Fedden served in the Women's Land Army and the Woman's Voluntary Service and as a driver for the NAAFI in Europe.

After the war was over, Fedden developed her own style of flower paintings and still lifes, reminiscent of artists such as Matisse and Braque.

[1]Fedden's subjects are often executed in a bold, expressive style with vivid, contrasting colours, although her work of 2005–6 uses a narrower tonal range.

In 1956, Fedden became a member of the London Group and became the chairperson of the Women's International Art Club, a post she held for three years.

In 1995, the writer and critic Mel Gooding wrote a monograph on Fedden's work tracing her long career up to her marriage to Julian Trevelyan and their life together on the Thames at Chiswick, London.

From 1984, Fedden held the post of President of the Royal West of England Academy (RWA), up until 1988,[2] the same year her husband Julian Trevelyan died.