The actor, who plays Gollum in the fantasy franchise, will be both behind the scenes and on screen again as the obsessive hobbit.
Serkis told Heat Vision that he will play a crucial role in filming the fourth instalment of the series.
He said: "There is really a sense of [director] Peter [Jackson] wanting people around him who totally understand the material and the work ethic.
"I will be very much on the live-action sets and locations helping Peter to tell the story."
Serkis has previously worked on motion-capturing King Kong and Gollum.
The Hobbit began shooting in Wellington, New Zealand last month.