"Mr Matari was arrested by Lebanese security forces in the northern city of Tripoli on August 31 last year, less than two weeks after he secretly flew to Lebanon, shocking his Sydney family," it said.
He was reportedly only days away from crossing the border into Syria after communicating with IS terrorists, including a foreign IS "coordinator".
Referencing Lebanese court documents, the ABC said Mr Matari told interrogators he had been encouraged to join IS in Syria by the head of an Australian charity.
SBS News visited the Sydney office of the charity on Thursday but it did not provide comment.
Mr Matari is reportedly due to be deported from Lebanon and could arrive back in Australia within days, where he will likely come to the attention of Australian counter-terrorism authorities.
Counter-terrorism expert Professor Greg Barton from Deakin University welcomed the news of Mr Matari's deportation.
"He should come back and face justice in Australia. That would be the most appropriate way of dealing with this," he told SBS News.