Named Wildlife Finder, the new online presence features 500 on-demand clips from 30 BBC series from the past three decades, including Planet Earth and Trials of Life.
Users can search through the content for their favourite animals, and also browse up to-date conservation information. More clips and related information will be added to the service going forward.
Celebrating the launch, veteran broadcaster Attenborough shared his 50 favourite wildlife TV clips of all time, including a spitting cobra in Life In Cold Blood and a deadly confrontation between chimpanzees and colobus monkeys in Trials of Life.
"I have selected some of my favourite clips. For me they represent not only a walk down memory lane but also a snapshot of the incredible diversity of life on Earth. It has always been my hope that, through filmmaking, I can bring the wonder of the natural world into people's sitting rooms," he said.
"The web has totally changed how we can link information, connect people and reach new audiences in an on-demand world. Wildlife programmes have always proved hugely popular and the appetite for discovery has led the BBC to bring these two worlds together."
Also commenting on the new service, BBC controller of knowledge George Entwistle said: "The BBC has a vast collection of world-class natural history content which we are now making available to viewers online. Through Wildlife Finder, we are able to offer viewers a year round on-demand natural history experience."
BBC Vision controller, multiplatform & portfolio Simon Nelson added: "Wildlife Finder is a fantastic example of the magic that can happen when the best TV, radio and new media teams come together.
"It's the world's finest natural history content connected together and made discoverable on the web by the cross-media expertise of the BBC."
The BBC also recently launched the Earth Explorers component of its website, in which natural history fans can follow production teams as they work on forthcoming wildlife programmes such as Frozen Planet.