Born in Melbourne, Marieke Hardy is the daughter of television producers and scriptwriters Alan Hardy and Galia Hardy and the granddaughter of Frank Hardy. Educated at Carey Baptist Grammar School and Swinburne Senior Secondary College in Melbourne, Hardy worked as a co-host on Melbourne's 3RRR radio programme 'Best of the Brat' from 1996, a role she continued until 2007; she shifted to ABC radio's Triple J in 2008, before leaving radio work in 2009 in favour of focusing more on writing. She also worked as an actress from a relatively young age, appearing in such programs as The Henderson Kids (series two), The Late Show, R. F. D. S., A Country Practice, Neighbours, True Love and Chaos, Raw FM, Stingers, Thunderstone, and Short Cuts (for the last two programmes, she also contributed scripts).
Hardy's first television scripts were for the long-running television sit-com All Together Now (1991), created by Pino Amenta, Philip Dalkin, and John Powditch; during the mid-1990s, she also acted as script assistant on Jonathan M. Shiff Productions' Ocean Girl. She followed this with work on crime drama Blue Heelers (2000) and scripts for several children's speculative-fiction television programs, including Jonathan M. Shiff Productions' Thunderstone (1999) and Horace & Tina (2001) and Barron Entertainment's Wild Kat (2001) (co-created by Paul Barron and David Ogilvy).
With the exception of children's television dramas Short Cuts (2002) and The Sleepover Club (2003), her subsequent work has focused more on adult drama, including scripts for Something in the Air (2001); McLeod's Daughters (2001); Always Greener (2002); Neighbours (1996-2003); Last Man Standing (2005), for which she was also co-creator and producer; Marx and Venus (2007); Spirited (2010); Packed to the Rafters (2008-2012); and Laid (2011-2012), for which she was also co-creator and producer.
Her most recent scripts are for the forthcoming series Mr & Mrs Murder (2013).
Hardy has also written columns for The Age; an award-winning blog, You Will Hate Me (which won a Bloggie for Best Australia/New Zealand Blog in 2008); and articles for Frankie magazine. Her first long work, You'll Be Sorry When I'm Dead, was published by Allen & Unwin in 2011.
Kate Miller-Heidke celebrates Hardy in her song 'Supergirl' (Curiouser, 2008).