In 2003, Gillies formed Tambalane with Wes Carr, initially as a songwriting project; they released a self-titled album in 2005 and toured Australia but subsequently folded.

He started as a quad drummer in the band The Marching Koalas, before forming a grunge group, Innocent Criminals, at the age of 12 with friends Daniel Johns, Chris Joannou, and Tobin Finnane.

Playing originally at school and other venues in the Newcastle area, they came to attention after a weekend music workshop at the Tanilba Bay Progress Hall funded through the Arts Council of New South Wales in March 1994.

[13] During an interview with the ABC's Australian Story in September 2023,[14] Ben revealed he had been dealing with anxiety ever since experiencing an acute psychotic break at the height of Silverchair's fame, when his first ecstasy pill, combined with a heavy marijuana habit, "pushed me over the edge".

In September 2020, Gillies was interviewed as a special guest on an episode of the Too Much of Not Enough Silverchair podcast, produced by Australian fan Daniel Hedger.