Lady Forrest had a great interest in fine arts. She had an interest in native plants, and was an accomplished painter of wildflowers. She was a founding member of the Wilgie Club, the first artists' society in Western Australia, and exhibited six wildflower watercolours in the Wilgie First Annual Exhibition of Paintings in 1890. After her death in 1929, her collection was bequeathed to the Art Gallery of Western Australia.
In September 1889 Ellis Rowan joined Margaret Forrest on a painting tour. At Boolantha Station, north of Carnarvon, and Geraldton, they painted desert flowers. Their joint exhibition at the Perth Railway Station Reading Room on 5 November is thought to have been the first art exhibition ever held in the colony.
Both the Margaret River and the Elvire River in the Western Australian Kimberley region were named after her.