Former Rockdale councillor Peter Poulos will replace another St George politician, John Ajaka, as a Liberal member of the NSW Legislative Council.
Mr Poulos defeated Sutherland councillor Kent Johns and two other candidates in a preselection ballot on Saturday.
Cr Johns turned his sights to winning the upper house vacancy after his prospects of gaining preselection for the federal seat of Hughes were dashed by opposition from senior party figures after the resignation of Craig Kelly.
A party source said Mr Poulos "won by a clear margin on the first ballot".
Mr Ajaka, 65, who was the president of the upper house since 2017 and a former minister, announced his resignation in February this year.
Mr Poulos, senior policy adviser to the Minister of Energy and Environment Matt Kean, was favoured to fill the vacancy.
Born and raised in St George, Mr Poulos attended Bexley North Public School and Sydney Technical High School.
He and his wife Vicki and their three young children live in the area.
Mr Poulos worked in the finance sector and served for 12 years on Rockdale Council and was deputy mayor for a year.
Mr Poulos said his main focus would be on road and rail infrastructure and cutting red tape for small business.
Sign up for our newsletter to stay up to date.