Cilliers Brink holds a Bachelor of Laws (LLB) degree from the University of Pretoria (UP) and is an admitted, non-practicing, Advocate of the High Court. In addition to being the DA mayoral candidate for Tshwane, he has worked as a legal adviser in a private practice. He has also owned his own paint retail and contracting business, but his career path has always led him back to politics.

At university he co-founded the UP branch of Democratic Alliance Students Organisation (DASO). In 2011 he was elected as a DA Councillor in Tshwane, and between 2016 and 2019 he served as Member of the Mayoral Committee for Corporate and Shared Services. In the 2019 general election he was elected as a DA member of the National Assembly. During his time in Parliament, he served as DA Shadow Minister of Cooperative Governance and Traditional Affairs as well as one of the party’s National Spokespersons. In March 2023 he was elected as Executive Mayor of Tshwane, a position he held until the withdrawal of ActionSA from the Tshwane Multi-Party Coalition in September 2024. In the meantime, he has stayed on as DA Councillor and leader of the opposition in Tshwane, and was recently elected as the Deputy Federal Chairperson of the party.