After his graduation in Clinical Oncology, Dr. Mohd Roslan started his Specialist career at Hospital Kuala Lumpur from 1989 to 2005. Together with his other colleagues, he headed the planning and design of the Institut Kanser Negara at Putrajaya as well as the Pusat Rawatan Oncologi of Hospital Sultan Ismail Johor Bahru, where he became the first Head of Department.
In 2006, he became the National Head of Oncology for the Ministry of Health as well as the State Advisor in Oncology for Johor until his retirement in 2016.
Whilst in Johor, he helped to reorganize the Oncology services by initiating the opening of two Clinical Oncology Units at Hospital Sultanah Nora Ismail at Batu Pahat and Hospital Pakar Sultanah Fatimah at Muar. He is also currently the Head of the Technical Unit of the Tunku Laksamana Johor Cancer Foundation, reaching out to help the less fortunate cancer patients undergo treatment.