Born in Northern Ireland and based in Glasgow, McMullan has a BA (Hons) in Sculpture from Cheltenham College of Art, a Masters of Fine Arts from the Glasgow School of Art and the School of the Art Institute of Chicago, and a Post Graduate Certificate in Learning and Teaching from University College, London. She has received a number of awards including a Scottish Arts Council Scholarship at the British School at Rome and undertaken residencies at the Nordic Institute for Contemporary Art, the Faroe Islands; Triangle Artist Workshop in Karachi, Pakistan; and Tramway, Glasgow. Her work has been shown nationally and internationally at major museums as well as through permanent public commissions.
McMullan currently works as part-time lecturer in the Department of Sculpture and Environmental Art at GSA where she is a contributor to the Reading Landscape Research Group. She is also part of the International research network Creative Centre for Fluid Territories (CCFT).