Prior to entering State Parliament he was general manager of his family's small business Barossa Fine Foods.

In January 2017, fourteen months before the 2018 state election, Knoll was promoted to the shadow cabinet, taking on the portfolios of Police, Emergency Services, Corrections and Road Safety.

[14] Knoll also advocated and secured the construction of twin tunnels to complete the North-South Corridor as part of the 2020 State Budget.

[18] Key elements in the Bill were rate capping, the establishment of behavioural standards for councillors and reductions of red tape to improve efficiency and lessen the burden on councils.

[21] Mr Knoll was found guilty of misconduct after attempting to sack members of the Adelaide Cemeteries board without authority.