Byrnes has worked as a journalist for over 20 years, including on the Independent, as a senior editor at the New Statesman and as editor of Qatar Foundation's quarterly international magazine.
In 2014 he took up a position as a senior fellow at Malaysia's Institute of Strategic and International Studies (ISIS).
According to the Sarawak Report, Byrne has worked with UK lobbyist Paul Stadlen who runs the communications team of the Malaysian prime minister Najib Razak.  Byrne, however, denies having ever worked for either Stadlen or the Malaysian government. 
- Mr Sholto Byrnes, Institute of Strategic and International Studies, accessed 13 May 2016
- More Smear Tactics And Black Ops By Najib's PR Hit Team - Anwar And Dr M Both Targets EXCLUSIVE!, 12 May 2015, accessed 13 May 2015
- Email from Sholto Byrnes to Spinwatch managing editor Melissa Jones, May 2016