McKenna was born in Lincolnshire in 1965, and studied Greek and Roman history and literature at St Hilda's College, Oxford.

[1] After college McKenna had a career in personnel management before changing to work in book-selling.

[12] In 2013 McKenna was the chair of the British National Science Fiction Convention, EightSquaredCon.

[19][20][21][22] She regularly attends fantasy conventions and hosted FantasyCon 2015's awards night, gives talks, and teaches creative writing courses.

[23][24][25] Financial Times reviewer James Lovegrove described McKenna's 2012 She-who-thinks-for-herself, as "a cunning, funny... feminist rewrite" of H. Rider Haggard's She: A History of Adventure.