He has been a member of the Queensland Legislative Assembly since 2004, representing three successive seats: Charters Towers (2004–2009), Dalrymple (2009–2017) and Hill (2017–present).

At the 2006 state election, Knuth was re-elected with a large swing, reverting Charters Towers to its traditional status as a comfortably safe National seat.

Charters Towers was abolished in a redistribution ahead of the 2009 state election, and Knuth opted to contest the new seat of Dalrymple.

[2] At the 2012 state election, despite a massive swing to the LNP statewide, Knuth easily retained his seat, defeating his replacement as LNP candidate by a nearly 2-to-1 two-party margin, winning enough primary votes to retain the seat outright.

Dalrymple was abolished in a redistribution ahead of the 2017 election, and Knuth transferred to Hill, essentially the northern portion of his old seat.