Wollongong City Council has agreed to erect a plaque at Fairy Meadow beach in memory of three-year-old Cheryl Grimmer.
In January next year it will be 50 years since the toddler disappeared.
She had been in the shower block at the beach when witnesses claim a man took her and ran off.
It is believed that she was strangled to death around an hour after her abduction on January 12, 1970, in the nearby suburb of Balgownie.
Cheryl's brother Ricki Nash, who was the last person to see her alive, is thrilled the council has agreed to honour his family's wishes.
"Some light to come out of years of darkness," Mr Nash told the Mercury.
"It means the world to our family that we can remember Cheryl in this way and we thank the council and the mayor for working with us," he said.
"I want it to carry a positive message, to remind people to always be careful, to be vigilant, a neighbourhood watch type message, something positive," he said.
"So on beautiful sunny days, when kids are enjoying the beach, we remind people to please enjoy the surrounds but be aware of the dangers."
Mr Nash and his brothers Paul and Stephen met with Wollongong Lord Mayor Gordon Bradbery on Friday to discuss ways to mark the 50th anniversary of Cheryl's death.
Cr Bradbery said it was early days but an "interpretive plaque" similar to the one pictured, was something the council was in favour of.
There was still some work to be done with the detail, and the selection of an appropriate location.
But it was likely such a plaque would be unveiled on January 12 next year, the Mayor said.
The Grimmer family plan to hold a walk in honour of Cheryl, and to engage the broader community.
Cheryl's disappearance had been without explanation for over 45 years, until a suspect was arrested and charged in 2017.
His trial was expected to take place at the NSW Supreme Court this month.
However, in February a judge ruled his detailed 1971 confession to the crime was inadmissible, and the charge was dropped.
In the absence of that interview, there was insufficient evidence for the case to proceed.
It was a blow to the Grimmer family who have been left without answers for all these years.