Warren graduated in 1991 and took up a position as a vocational trainee at a busy NHS dental practice in the West Midlands. Shortly after completing his vocational training, he purchased the practice. During that time, he was also a part-time clinical lecturer in Birmingham dental school and a member of Sandwell LDC. In 2003 he moved to Mid Wales and worked part-time for the community dental service treating mainly paediatric and special care patients and as an associate dentist in a predominately private practice. In 2009 he became the full-time clinical lead for Powys Teaching Health board. He is currently the Associate Dental Director for PTHB and Deputy Dental Director for Welsh Government.