Annie Haynes was born in Leicestershire, England. Her parents were Edwin Haynes, an ironmonger, and his wife Jane. After Annie's father left his family, she, her younger brother, and their mother went to live with Jane's parents, who worked at Coleorton Hall, near Coalville, a 19th-century mansion.
It was an experience that may have given Annie insights into the life of the aristocracy that would serve her in later life as she wrote mysteries set in large country houses.
By 1908, she was living in London and moving in literary and early feminist circles. At first, she wrote serialized romance novels for newspapers with titles such as Lady Carew's Secret and Betrayed by a Woman. She developed an interest in forensics and criminology and eventually introduced these elements into her work, beginning with her first crime novel, The Bungalow Mystery (1923), published when she was in her fifties. Her mystery novels were highly acclaimed and though she is largely forgotten today, in her own time she was considered on par with classic authors Agatha Christie and Dorothy L. Sayers. The Abbey Court Murder (1923) was the first of her books to feature Inspector Furnival of Scotland Yard, who also appeared in two subsequent novels, The House in Charlton Crescent (1926) and The Crow's Inn Tragedy (1927.)
In 1928, she started a new series with Detective
Inspector Stoddard in The Man with the Dark Beard. Annie Haynes suffered for many years from severe rheumatoid arthritis, and died of heart failure in 1929 at about age 64. She had completed a dozen novels, including Who Killed Charmian Karslake? published posthumously in 1929 and The Crystal Beads Murder, which was completed by a friend and published the following year.