[1] Following the LNP's electoral victory in 2012, Walker was appointed Assistant Minister for Planning Reform on 3 April 2012.
[2] On 17 February 2013, then Premier Campbell Newman appointed Walker as the new Minister for Science, Information Technology, Innovation and the Arts after the resignation of Ros Bates.
[3] Following the LNP's defeat at the 2015 Queensland election, Walker was succeeded as Minister by Leeanne Enoch (Science and Innovation) and Premier Annastacia Palaszczuk (Arts).
Despite the statewide defeat of the LNP, Walker narrowly retained Mansfield, a noted bellwether seat, becoming its second opposition member.
The first, fellow Liberal Frank Carroll, served in opposition for a few months in 1995 and 1996 before a by-election elevated the Coalition to minority government.