Generations of families from across the New South Wales south coast joined celebrations at Killalea State Park on Sunday as they marked its permanent protection from developers.

The popular park and beach 'The Farm' are known for their exceptional surfing and natural beauty, as well as important Aboriginal cultural heritage.

For more than three years, the community has fought plans by developers to build a function centre and luxury cabins on the site.

On July 1, the 260-hectare park entered the management of the National Parks and Wildlife Service (NPWS) as a Regional Park, managed under the NPWS Act.

Fiona Smith was at the celebrations to mark the park's protection with her family.

"It's a magic place, it's the jewel in the Illawarra crown," she said.

"I used to live here on the farm. For my family it is part of our history, and it should be protected for my family's future generations as well as everyone else's.

"My Dad was an avid surfer, and I remember chasing bunnies and picking berries, this is where I took my first steps."

Illawarra elder Aunty Lindy Lawler provided a powerful welcome to country for the event.

"You made this land safe for everyone, your help was incredible," she told the 200-strong crowd.

"All that are here today, you have respected this land. It will walk with you through the days.

Collective effort

In May 2021, with the support of the Surfrider Foundation, 681 people paddled out in protest against the expansion of the park.

Convener of the Save Killalea Alliance Ben Morgan told Sunday's crowd that was a powerful message to the state government.

"This place is so beautiful, we just know this place is protected for the current generation and future generations to come," he said.

"It's been an amazing outcome, absolutely phenomenal."

Shellharbour MP Anna Watson was the first politician to raise the issue of stopping development at the park in the parliament.

She said she would work closely with NPWS to make sure the future management of the park met the community's expectations.

Shellharbour Mayor Chris Homer said the campaign to protect the park was the work of many.

"Surfers came together, the ecologists came together, the coastal lovers came together," he said.

"We can really see our environment is under threat, an environment on the edge of a major city and we are growing ... but people want to come here.

"They want to come and experience what we have experienced most of our lives and we want to leave that for our children, the experience, as well."

From August, the NPWS will start consultation with the community to develop a new plan of management for the park.