In April 2009, he was elected as a Member of the Western Cape Provincial Parliament for the Democratic Alliance. He was sworn in as a Member on 6 May 2009. Newly elected Premier Helen Zille announced that Grant would become the Provincial Minister of Education, succeeding Yousuf Gabru. He was inaugurated as Provincial Minister on 7 May 2009 by Constitutional Court Judge Yvonne Mokgoro.[4]
In the general election of 7 May 2014, he was re-elected for a second term as a member of the provincial parliament. Zille announced that Grant would now become Provincial Minister of Transport and Public Works, succeeding Robin Carlisle. He was inaugurated by Western Cape High Court Deputy Judge President Janette Traverso on 26 May 2014. Debbie Schäfer succeeded him as Provincial Minister of Education.[5]
Grant left the provincial parliament after the 2019 elections, although he was elected to another term as an MPP. Newly elected Premier Alan Winde appointed him as a special adviser.[6][7] In November 2021, he retired from the provincial government.[8]