Seacole was born Mary Grant in 1805, in Jamaica. She is of Scottish and Creole descent (mixed-race). Growing up, Seacole learned of herbal medicine in the Caribbean. She visited Britain at age 15, and since then she occasionally visited the Island, going backwards and forward between Britain and the Caribbean. She married Edwin Seacole in 1836; he died eight years later, making Seacole a widow.
She is known for her contribution during the Crimean War (1853-56). She was declined to assist in the war office, despite this she continued to travel and set up a hotel in Britain, which assisted soldiers wounded in battle.