Roger Simpson completed a Bachelor of Laws at Auckland University in 1968, then practised law for three years in New Zealand.
After moving to Australia in the early 1970s, he became an award-winning film and television writer. As was common with script-writers in that era, his earliest scripts were for Crawford Productions: he wrote for Homicide (1972-1974) and Division Four (1972-1975). At the same time, he was writing scripts for New Zealand television, including the telemovie Richard Pearse and the historical children's television programs Hunter's Gold (1977) and Children of Fire Mountain (1979): the latter, for which Simpson was sole script-writer, won Feltext Television Awards for Best Drama and Best Script.
In Australia in the 1970s and 1980s, Simpson wrote a number of telemovies and mini-series, including The Trial of Ned Kelly (1977), Players in the Gallery (1980), I Can Jump Puddles (1981), Squizzy Taylor (1982), Sword of Honour (1986), Nancy Wake (1987), and Darlings of the Gods (1989).
He als contributed episodes to such television series as Power Without Glory (1976), Young Ramsay (1980), and Learned Friends (1983).
In 1989, Garry O'Connor published Darlings of the Gods: A Novel Based
on Scripts by Roger Simpson and Graeme Farmer and on Garry O'Connor's
'Darlings of the Gods: One Year in the Lives of Laurence Olivier and
Vivien Leigh'.
His writing in the 1990s was weighted more towards television series than telemovies, with scripts for Skirts (1990), Snowy (1993), Halifax f.p. (1994-2000), Good Guys Bad Guys (1998), and Stingers (1998-2002). He also wrote the script for 'His Master's Ghost', an episode of the Australian Children's television Foundation's anthology series More Winners.
He also shifted into the role of producer in this decade, a role he would occupy successfully for some two decades. In 1992, he produced the Australian film The Nostradamus Kid, and for 25 years (to 2006), he co-produced with Roger Le Mesurier many successful Australian television dramas, including Halifax f.p., Good Guys Bad Guys, and Stingers.
Since 2000, Simpson has contributed scripts to such television programs as Something in the Air (2000), Silversun (2004), Satisfaction (2007-2009), and Bikie Wars: Brothers in Arms (2012), as well as writing the telemovies Big Reef (2004) and Life (2005), and the movie-length pilot for the ill-fated television series The Angel Files (2002), six episodes of which were produced but never aired after the disappointing ratings for the pilot.