Bush began painting at 62 after an experience she described as "visionary". Her work is strongly simplistic, and many of her paintings depict Christian themes. She painted mainly in oil on canvas. She also decorated the walls and furnishings of her home with her work.
Bush was awarded the MBE in 1997, receiving it as part of the celebrations surrounding the Queen's Birthday on 15 June 1998. She was also awarded the Heritage Award of the Cayman National Cultural Foundation. The foundation also published a book of her paintings, My Markings...the Art of Gladwyn K. Bush, and she has been profiled in numerous books of outsider art. Her paintings are in private collections worldwide, and may also be seen at the American Visionary Art Museum in Baltimore, Maryland.