Lawyer and think-tank executive Julian Leeser has easily won Liberal preselection for Berowra, the seat held by retiring senior party figure Philip Ruddock.
Mr Leeser, who is a former executive director of the conservative Menzies Research Centre, took out 97 of 114 votes on Saturday afternoon.
Mr Ruddock announced he would not contest the next election after he was announced as Australia's first special envoy for human rights.
"Congratulations Julian Leeser on an outstanding win in preselection for Berowra," Mr Ruddock said on Twitter.
"Now the big job begins."