Australian counter-terrorism authorities arrested the 16-year-old teenager from his western Sydney residence late Sunday night, just hours before people gathered to commemorate the nation's fallen serviceman and women on the anniversary of the First World War landings in Turkey, Xinhua news agency reported.
"At this stage we believe it was one person by himself," New South Wales state Police Commissioner Andrew Scipione said on Monday.
"The risk from this particular threat has been thwarted."
Last year, five teenagers were arrested in Melbourne, along with a 14-year-old boy in Britain, for allegedly planning a terror attack at similar events.
"In Australia and around the world, the age of people radicalised is getting younger, with online grooming tactics similar to those used by sexual predators," Australian Federal Police (AFP) NSW state commander Chris Sheehan said.
In December 2015, Australian counter-terrorism authorities arrested a 20-year-old man and a 15-year-old teenager in connection with an alleged plot targeting Australian government buildings, including the AFP headquarters in Sydney.
In February, the teenage bride of an Australian terror suspect was arrested by counter-terrorism authorities for allegedly possessing a knife, an Islamic State flag and documents relating to a terror attack. Her husband is already in custody over terror related charges.