The veteran evangelist, who worked with Christian organisation Scripture Union for over 30 years, died of suspected heart failure on August 2, a statement on a website run by his son Stephen said.
"We have now lost him but are comforted by the knowledge that he is now with his Lord," Stephen wrote on behalf of Mr Shelley's wife Daphne, their other children, grandchildren and great grandchildren.
According to Stephen, Mr Shelley had been working together with him on their latest project, A to Z Ministry with Children, the night before his death.
"I shall finish this project now that he is gone," Stephen wrote. "I started Shelley and Son so that his skills, knowledge and insight in children's ministry would not be lost."
"I am so glad that we were able to produce so much while we still had time."
NSW Scripture Union Chairman, the Rev Simon Flinders, described the Mr Shelley as a 'Scripture Union legend' who share the gospel to thousands of children across the state with passion and creativity.
"No-one in our movement's history has done more to dignify ministry to children than Owen," Rev Flinders said.
"His zeal for the gospel, and his creativity in telling it, have together been an inspiration and a model for many."
A funeral will be held on August 12 at Narwee Baptist Church. The Dean of Sydney, Phillip Jensen, is scheduled to preach.
In recent years, Mr Shelley had partnered with his son to create ministry resources such as interactive bible stories and quiz games which are designed to be used in the new digital age.