Florence Green was born at Edmonton, London to Frederick and Sarah (nėe Neal) Patterson. She joined the Women’s Royal Air Force in September 1918 at the age of 17, where she served as an officers’ mess steward. She worked in the officers’ mess at RAF Marham and was also based at Narborough airfield.  She moved to King’s Lynn in 1920, after her marriage to Walter Green. Her husband, a railway worker, died in 1975, aged 82, after 55 years of marriage. She lived in King’s Lynn with her 90-year-old daughter, May (born 1921), until November 2011 when she moved into a care home. In January 2010, she was publicly identified as, at that time, the oldest living female veteran of the First World War.  On 19 February 2011 she celebrated her 110th birthday, becoming a supercentenarian—one of just 10 living in the United Kingdom, all women. With the death of Claude Choules on 5 May 2011, Green became the last known living veteran of the First World War. On 20 July 2011, the Gerontology Research Group verified her age, and listed her as an official supercentenarian.

It was reported that when asked what it felt like being 110, she replied, “Not much different to being 109”. In 2011, an image of Florence Beatrice Green became part of a subject for the “WWI Centenary Mural” created by Christian Cardell Corbet and Benjamin Trickett Mercer. At the time of her death, Green had a son and two daughters, as well as four grandchildren and seven great-grandchildren. Before her death on 4 February 2012, aged 110 years and 350 days, she was West Norfolk’s oldest resident, the second-oldest person in Norfolk, and the sixth-oldest in the United Kingdom.