The title recognises an area with exceptional quality of starry nights and a commitment to protecting the noctural environment.
Such dark-sky area designations aim to restrict artificial light pollution so that night skies can be observed and enjoyed to their fullest potential.
Tourism Niue said the protection added to current measures, including a marine reserve which was 40 percent of Niue's exclusive economic zone.
The Huvalu Forest Conservation area, which contains some of the world's most threatened flora and fauna, is also protected.
Niue now had a dark-sky community and two dark-sky sanctuaries, said Tourism Niue chief executive Felicity Bollen.
"It's a huge undertaking for us because it shows clearly to the rest of the world that we take very seriously the sustainability of our environment and culture and how precious we hold the land, the sea and now the sky."
Celebrations were held on Sunday to mark the island's milestone achievement.
Niue now has dark-sky status from the southern edge of Mutalau Village to the northern edge of Hakupu Village.
Both the marine reserve and forest sanctuaries cover 75 percent of the island's land mass, Ms Bollen said.
The initiative, championed by Niue Tourism, received support from the government and community with the whole island coming together to support the project and make the changes.
Andre Siohane, of the Ministry of Infrastructure in Niue, said the government was committed to the protection, management and enhancement of the nation's dark skies.
"Some of the significant measures undertaken by the government include full streetlight replacement for the entire island and the upgrading of domestic private lighting," he said.
Ms Bollen said dark skies and dark-sky tourism became one of the hottest trends last year.
She said people could travel to Niue to admire the dark sky, and learn about the culture and the mythology from the people who lived on the land.
"Niue is always looking for tourism opportunities, tourism products, and services which have a minimal, negative impact on the environment and culture," she said.
"Dark sky absolutely meets that criteria."
Ms Bollen said they had trained "dark-sky ambassadors" who had set up business in the villages and would take tours around the country.
That was a great economic contributor for Niue and for small businesses, and Niue was proud to receive such an important acknowledgement from the IDA.
To be the first country to become a dark sky nation was a massive accomplishment for a small Pacific nation with a population of just over 1600 people, she said.
"The stars and night sky have a huge significance to the Niuean way of life, from a cultural, environmental and health perspective.
"Being a dark sky nation will help protect Niue's night skies for future generations of Niueans and visitors to the country."
Ms Bollen said the new status sat well with Niue's ethos of protection and conservation at all cost - that tourism had to comply with those standards.
New Zealand couple Richard and Gendie Somerville-Ryan researched and wrote Niue's application, after having previously carried out a successful bid for Great Barrier Island to become a Dark Sky Sanctuary.
Mr Somerville-Ryan said the journey to protect the island's pristine night skies began in mid-2018 when they formed a small team with Niue Tourism.
"We then began to share our excitement about the quality of the island's dark sky with the wider community," he said in a statement.
"Niueans have a long history of star navigation and a life regulated by lunar cycles and star positions.
"The knowledge of the night skies, held by the elders in the community, has been passed down through the generations."
Niuean elders now hope the passion to learn the cultural history of the stars is re-ignited in the younger generations.
Elder and cultural guardian Misa Kalutea said Niue's skies had been appreciated for centuries.
The new status added more emphasis to the importance of Niue's traditional knowledge - "providing a reason for the retelling and sharing of this knowledge before it's lost".
The IDA celebrated Niue's achievement in Arizona where the official announcement was made on Sunday.
Niue's official Dark Sky recognition is set to provide a significant economic opportunity for the small Pacific island with a growing global interest in 'Astro-tourism'.