Mr Caldwell beat four other candidates during a party vote on Saturday.
The unsuccessful LNP candidates were disability advocate Dr Dinesh Palipana wealth manager Owen Caterer, Craig Hobart and businesswoman Fran Ward, the only female contender.
Mr Caldwell will take on Labor's Letitia Del Fabbro, a nurse educator at Griffith University, at the July 15 by-election for what has historically been a safe coalition seat.
Ms Del Fabbro was endorsed by Labor to take a second tilt at the federal seat following her unsuccessful run last year.
After 11 years on the council, Mr Caldwell has generated a strong local profile as planning chair.
The by-election was triggered by the resignation last month of the LNP's Stuart Robert.
Mr Robert has faced calls he be referred to the National Anti-Corruption Commission over his alleged involvement with a consulting firm that helped companies win government contracts.
A government inquiry identified 19 contracts worth $374 million requiring further examination.
Mr Robert has denied any wrongdoing and says the government inquiry did not find any misconduct.
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