Warren ran a busy NHS practice in the West Midlands before moving to Wales in 2003 where he started working in the community dental service and as an associate in a mainly private dental practice. In 2010 he took up the position as the clinical dental lead for Powys Teaching Health Board and has responsibility for the governance of dental services delivered in Powys. In January 2020 he was seconded as a part time deputy chief dental officer for Welsh Government. He still retains his substantive role as associate dental director for Powys Teaching Health Board. Past appointments including being chair of Welsh Dental Committee, former member of Sandwell Local Dental Committee and part time clinical lecturer at Birmingham Dental School. Clinically he has a special interest in endodontics.