He was born in Newcastle, New South Wales. His mother Annette Gillies worked in the cafeteria at Newcastle High School. His father, David Gillies works as a plumber. Gillies has an older sister named Kristie. The Gillies family is a part of the Surfrider Foundation, which promotes clean ocean water. Furthermore, Gillies is an excellent surfer, and cook.

Besides Ben Gillies was a quad drummer in "The Marching Koalas" and he taught his friend Chris Joannou of Silverchair how to play bass in three months. Gillies also plays the guitar and bass.