[4] Mohd Riza started off with Brunei Administrative Services (BAS) as the Director of the Land Transport Department.

[4] From May 2020 to June 2022, Mohd Riza held the position of permanent secretary overseeing Civil Service, Welfare, International Affairs, and Media.

Prior to that role, he served as permanent secretary in charge of Media and Cabinet affairs at the PMO from August 2016 to April 2020.

[5] Preceding this, he was the deputy permanent secretary responsible for Corporate and Governance matters at the PMO from November 2015 to August 2016.

His career also includes a stint as deputy permanent secretary at the Ministry of Communication from June 2014 to November 2015, and as deputy permanent secretary focusing on Entrepreneurship and Industry Development at the Ministry of Industry and Primary Resources from September 2010 to June 2014.