Former political staffer Slade Brockman will fill the casual senate vacancy left by the retiring Chris Back.
Mr Brockman, Finance Minister Mathias Cormann's former chief of staff, was announced as West Australia's next federal senator on Saturday night in a tweet by the WA Liberals.
Mr Brockman, who ran unsuccessfully for a senate spot in the 2013 election, edged out several other candidates including former WA Parliament speaker Michael Sutherland.
He holds a Bachelor of Laws from the University of New England, and worked as Senator Cormann's chief of staff between 2008 and 2013, according to his LinkedIn profile.
Mr Brockman was a policy director for the Pastoralists and Graziers Association of WA and a farm manager before that.
Fellow WA Liberal Dean Smith tweeted his support for the soon-to-be senator following the announcement.
"A great addition to our WA Senate team and another strong voice for regional WA and #GST reform."
Senator Back announced his retirement in June after eight years in office.