Over 9 million people tuned in to watch the first episode of the new series as it aired on Sunday on BBC 1.
This is even more viewers than the beginning of the original series had a decade ago, when it debuted with 8.74 million viewers.
The popularity of BBC iPlayer means that even more viewers are expected to watch via the catch up service.
The viewing figures already make this one of the most-watched shows this year, with the episode ranking amongst The X Factor, Strictly Come Dancing and The Great British Bake Off.
Planet Earth 2 saw viewers drawn into the world of island animals, featuring sloths, komodo dragons and migrating red crabs.
The series has been filmed over a huge 2,089 days, with 117 filming trips across 40 different countries. New filming techniques have been used to allow viewers to get closer to the animals than ever before.
Head of the BBC’s Natural History Unit, Julian Hector, said the new series was a fascinating new insight into the world of animals.
“Audiences love Sir David’s authenticity and the craft of the programme-makers that give us a window on the motivations of the animals. When so much is going on in the human world, that the natural world has an agenda all of its own, regardless, gives us a place to escape.”