Lady Barker was born Mary Anne Stewart in Spanish Town, Jamaica, where her father was Island Secretary. She was sent to England for her education. In 1852, she married Captain George Robert Barker of the Royal Artillery, with whom she had two children. A few years later, Barker was knighted for his leadership at the Siege of Lucknow during the Indian Mutiny, making her Lady Barker. In 1865, after Barker's death, she married Frederick Broome, a Canadian-born sportsman and future diplomat 11 years her junior, who was in London on a visit from New Zealand. She departed with him for New Zealand, leaving her children behind in England. The couple lived at Steventon, a sheep station, for three years before selling out and returning to London.
The experience would provide a rich well of material for Lady Barker, and several of the works she produced became classics of New Zealand literature. Poems from New Zealand appeared in 1868, followed by The Stranger from Seriphos (1869). Then she published Station Life in New Zealand (1870), a collection of her letters home. Over the next eight years, she produced 10 more books, including Station Amusements in New Zealand (1873) and First Lessons in the Principles of Cooking (1874). This book led to her being appointed Lady Superintendent of the National Training School of Cooking in South Kensington.
She also was a journalist, writing articles for The Times. In 1875, Broome was appointed Colonial Secretary of Natal in South Africa, and she accompanied him there. His subsequent posts were in Mauritius, Western Australia, Barbados, and Trinidad. Drawing on her travels and experiences in these countries, Lady Barker published A Year's Housekeeping in South Africa (1880) and Letters to Guy (1885). Broome was knighted in 1884, and thereafter she styled herself Lady Broome. She published the last of her 22 books, Colonial Memories, under this name.