Tim Costello, World Vision Australia's chief advocate, is stepping down after 15 years with the organisation.

Costello, who is one of Australia's most renowned Christian voices on social justice issues, will continue to lend his expertise to the organisation on issues of global poverty.

Tim Costello

Tim Costello

“After so many years at this wonderful organisation, I am no less passionate about the work that we do around the world," the 64-year-old said in a statement. "While this marks the end of my time as an employee, I remain a committed supporter and a passionate member of the alumni."

Costello first joined World Vision Australia in 2004 as CEO and in 2016 moved into the role of chief advocate, working alongside new CEO Claire Rogers. He said his time with World Vision had been an expression of his life's purpose.

“I've been to some of the most difficult of places in our world, and what has always struck me is the enduring hope of the people I meet. That’s what has always kept me going; the notion that I could play but a small part in realising those hopes.”

Costello expressed his appreciation for being able to step into the position of chief advocate.

“I leave knowing that the leadership of World Vision Australia has been well transitioned, excited for its future direction and encouraged for the impact it will continue to have on the world’s most vulnerable children,” he said.

Rogers paid tribute to Costello's "unwavering dedication, passion and humanity".

“In both his role as CEO and chief advocate Tim has been instrumental in helping grow World Vision Australia to become the nation’s best-known humanitarian organisation. I am thankful to have inherited the leadership of this incredible organisation with the impact of Tim’s legacy,” she said.

“He is an inspirational and much-loved figure not just in Australia but around the world and I thank him for his extraordinary service to our organisation and the world’s most disadvantaged children.”

Shannon Adams, chairman of World Vision Australia, also paid tribute to Costello, saying World Vision "would not be the same today without Tim’s fearless leadership and steadfast devotion to lifting children and communities out of poverty".

As well as continuing to advise World Vision, Costello will also be continuing in his roles as chair of the Community Council of Australia, director of the Alliance for Gambling Reform and executive director of Micah Australia.