Mary Ann McCracken was born in Belfast, Co. Antrim on the 8th of July 1770 to Presbyterian parents, Captain John and Ann McCracken. As a child, she was sent to a progressive school wherein girls were educated to the same level and in the same subjects as boys, and she herself excelled in mathematics.
Throughout her lifetime, Mary Ann was highly involved in charitable works. As a child she made regular visits to Belfast's first Public Charitable Institution, eventually taking a place on the Institution's committee. She also ran an all-religions Sunday school for the poor children of the city. This was done with the aid of her brother, Henry Joy McCracken. Henry Joy was highly involved in Irish Republicanism and it wasn't long before Mary Ann also became interested in the cause. In 1798, when her brother found himself on the losing side of the Battle of Antrim, Mary Ann aided Henry Joy and his comrades in their attempted escape to America. While they were in hiding, Mary Ann brought them clothes and food, but the men were eventually found out when Henry Joy was recognised and captured in Carrickfergus. When her brother was executed, Mary Ann took in his illegitimate daughter and raised her as her own.
Mary Ann had a keen sense of social justice and was committed to the cause of ending the tithe system which crippled the poorest people of Ireland. She was also a firm abolitionist and abstained from sugar to prove her point that the slave trade needed to be stopped. She also strongly advocated for equality of the sexes and was highly involved in early suffrage campaigns. She spoke at length on the need for reform in Ireland's prison systems, a cause which she understood all too well after her brother's time spend in the prison system. She was dedicated to the rights of children and campaigned for an end to be put to the use of boys in chimney cleaning.
Along with her sister Margaret, Mary Ann established a muslin business in Belfast. As a socially conscious woman, she made sure that the rights of the workers were respected and adhered to at every turn.
Throughout her life, Mary Ann served on a number of committees, including that of the Belfast Workhouse.
Mary Ann McCracken died in Belfast on the 26th of June 1866 at the astonishing age of 96. She is buried in the Clifton Street Cemetery in her native Belfast.