Sinéad McCoole was born in New York in 1968. She came to live in Ireland at the age of four with her Irish-born parents, Michael and Barbara McCoole (nee Folan) and her siblings Fiona and Ciaran. Sinéad spent her childhood in Limerick before moving to Dublin in 1987.

She is a graduate of University College Dublin with an Honours degree in History and History of Art (1990) and a Masters in Modern Irish History (1992). She is married to Eamon Howlin and they have two children Eve and Edward.

In 2005 she moved to Mayo and works at the Jackie Clarke Collection. In 2012 she was appointed to the Expert Advisory Group on the Decade of Centenaries.