She is best known for playing the roles of Nellie Cameron on the television series, Underbelly: Razor (2011), Lucy in House Husbands (2012–2014), and Rose Anderson in The Doctor Blake Mysteries (2015–2018).

McGahan grew up in Coorparoo, Queensland, attending to Brisbane Girls Grammar School and then studied for a Bachelor of Fine Arts (Acting) at QUT, graduating in 2010.

Her most notable appearance to date is starring as Nellie Cameron in the hit Australian TV series Underbelly: Razor, in which she plays a 16-year-old 1920s prostitute from a wealthy background who influenced some of the era's most powerful men, for which she won the Inside Film 'Out of the Box' Award and was nominated for two Logies.

Based closely on real characters, she plays opposite Brandon McClelland as the Australian soldier Norval 'Pat' Dooley, who married Haynes in 1917.

[7] She is no longer heavily involved in the church as an institution, and in 2021 stated that she creates work that ‘prioritises a defiant female gaze to explore experiences of embodiment, motherhood, sexuality and spirituality’.