"Its value to humanity is priceless."
The MPA will come into force in December 2017 and include a 1.55 million km2 - or 72 per cent of the Ross Sea - 'no-take' zone which forbids all fishing.
Other sections will permit some harvesting of fish and krill for scientific research.
CCAMLR's Scientific Committee first endorsed the protection proposals for the Ross Sea put forward by the United States and New Zealand in 2011.
It has taken five years to refine the proposal and work through the specific details such as the location of the boundaries.
The decision is notable because all 25 countries involved in CCAMLR had to agree.
"The monumental collaboration between 25 country members sets a benchmark for the world to work collaboratively to protect the entire planet," Ms Ross said.
"We have a finite time to make an infinite difference."
Last February, she and her uncle, James Hood Ross from UK, voyaged to Antarctica to commemorate the 175th anniversary of the discovery of the Ross Sea and Ross Ice Shelf. They were the first members of the family to set foot on the ice shelf since that expedition.