The department's documentaries have included Planet Earth II and Blue Planet - both narrated by Sir David.
The 91-year-old will join the unit's head Julian Hector.
They will discuss some of the most ground-breaking moments throughout its 60 years of programme making.
Sir David said: "I'm delighted to be at the Edinburgh TV Festival to recall the history of what was the first Natural History Unit to be set up in the world and to celebrate some of its milestones."
Mr Hector said: "I grew up with The Living World presented by Peter France on Radio 4 and was studying zoology at university by the time Sir David's Life On Earth was first broadcast in 1979 on BBC 1.
"The NHU has been part of my life ever since, and I look forward to sharing with the TV Festival all of the astonishing work that goes on behind the scenes to make these incredible series."
Sir David has been breaking ground in nature documentaries since the 1970s when one of his first televised expeditions, A Blank On The Map, saw him trek through the central New Guinea highlands to meet a group of tribespeople  never before seen by Europeans.
Most recently, he lent his charismatic voice to the second series of Planet Earth, which won a Bafta earlier this year for best specialist factual programme.
His appearance at the festival will mark a special moment for visiting fans, not least the event's own director Lisa Campbell.
"It's long been an ambition of mine to welcome Sir David to the festival and I have no doubt that this will be a remarkable and historic session," she said.
The Edinburgh International Television Festival runs from August 23-25.
Sir David Attenborough will join the line-up for this year's Edinburgh International TV Festival as he celebrates the 60th anniversary of the Natural History Unit.