Ahead of the May 2019 general election, Bosman placed 25th on the Democratic Alliance's candidate list for the Western Cape Provincial Parliament. The Democratic Alliance won 24 seats, initially declining him a seat. Provincial minister Donald Grant opted against serving in the provincial parliament to become Premier Alan Winde's adviser. Bosman was named his replacement and filled the seat on 22 May 2019. In June 2019, he was elected chairperson of both the Standing Committee on Social Development and the Petitions Committee by the respective committees.
