It has become Wales' second and only the 10th destination in the world to be granted the status of an international dark sky reserve.
It means the quality of the night air is outstanding and real efforts are being made to reduce light pollution.
The successful bid was announced at the Dark Sky Institute in Arizona, United States.
"Receiving this designation is very good news for the residents, businesses, visitors and the wildlife of Snowdonia," said Emyr Williams, chief executive of Snowdonia National Park Authority.
"Unfortunately, the opportunity to enjoy the night sky and its stars is in decline, the living patterns of nocturnal creatures are dwindling and as light pollution is rising, it contributes to these deteriorations.
"However, with this designation, the area's wildlife will be improved, the quality of the environment will be protected, there will be a new natural attraction to attract new visitors to Snowdonia on quiet periods of the year, the local economy will be improved and the dark sky above Snowdonia will be protected for future generations."
The night sky above the Snowdonia National Park has been granted special protection.