Currently performing as Jill Lorean, O'Sullivan has been a member of bands Sparrow and the Workshop, Bdy_Prts and Three Queens in Mourning, as well as contributing to records by Frightened Rabbit, James Yorkston, Roddy Woomble, Broken Chanter, The Grand Gestures, The Fruit Tree Foundation and the Gral Brothers.
O'Sullivan moved to London in 2005 to pursue a master's degree in sociology, completing her studies in Glasgow in 2007, where she soon after formed Sparrow and the Workshop with Nick Packer and Gregor Donaldson.
[3] O'Sullivan has also released a collaborative album with renowned musicians Alasdair Roberts, Alex Neilson and Bonnie "Prince" Billy under the moniker Three Queens in Mourning (2020).
[4] In addition, she collaborated with Sean Cumming (John Knox Sex Club) on storytelling project Do the Gods Speak Esperanto,[5] released in 2017.
Over the years O'Sullivan has also worked with Scott Hutchison, Emma Pollock and James Yorkston amongst others, and toured with the likes of The Pogues and The Brian Jonestown Massacre.