The programme will alert viewers to the dangers facing the planet, hoping for a similar effect to last year's Blue Planet II, which highlighted pollution in the oceans.
The BBC holds up its natural history documentaries as something it does better than anyone else. But Netflix wants to encroach on that territory, as it did in drama by producing the critically acclaimed House of Cards and The Crown.
While Attenborough is a free agent and has made shows for Sky, his association with the BBC has lasted 40 years and he is regarded as one of the corporation's biggest stars.
Launching Our Planet, Lisa Nishimura, the vice-president of Netflix Original Documentaries, said: "We are delighted Sir David Attenborough will voice the series and that Netflix, as a global platform, is able to bring this vital and magical series to an audience of over 190 countries."
Our Planet is a collaboration with Silverback Films, the production company run by Alastair Fothergill. A former head of the BBC's Natural History Unit and the director of Blue Planet, Planet Earth and Frozen Planet, Fothergill described the new series as "our most ambitious endeavour to date".
The announcement came in the week that BBC One broadcast its latest series voiced by Attenborough, Dynasties. Lord Tony Hall, the BBC director-general, said: "There is one essential presence at the heart of this series and that's David Attenborough."
Charlotte Moore, director of content at the corporation, recently held up Blue Planet II as an example of programming that sets the BBC apart from its commercial rivals.
Characterising Netflix and Amazon as media companies with an "insatiable greed for data-gathering", commissioning shows by algorithm, Moore said Blue Planet II was such a success because it came from "a brilliant, trusted storyteller".
She said: "The success of the series owes so much to David Attenborough - one of the most trusted, authoritative and admired voices on TV. The level of trust that audiences have in David is extraordinary." Attenborough, giving the World Wildlife Fund's Planet Address last week, said he was proud of the new show.
"Our Planet will take viewers on a spectacular journey of discovery, showcasing the beauty and fragility of our natural world," he said.
"Today we have become the greatest threat to the health of our home but there's still time for us to address the challenges we've created, if we act now. We need the world to pay attention. Our Planet brings together some of the best film-makers and conservationists and I'm delighted to help bring this important story to millions of people worldwide."
• Sir David attenborough's new show, Our Planet, premiers on April 5.