Authorities will be able to prosecute those lying about their age to minors online under new legislation introduced to Federal Parliament.
The legislation will also target predators planning to cause harm to, or engage in sexual activity with, a child.
Offenders face up to 10 years in prison.
The proposed legislation follows a decade-long campaign by Sonya Ryan, whose 15-year-old daughter, Carly (pictured), was murdered by a 50-year-old man posing as a teenager online.
Gary Newman pretended to be a teenage musician from Melbourne for more than a year before he met Carly in person, saying he was the musician's father.
Newman became angry when Carly rejected him, but later managed to persuade her to meet him again at Port Elliot, South Australia, where he bashed her, pushed her face into the sand, suffocated her, and threw her into the water to drown.
Cyber safety expert Susan McLean welcomed the changes, but said legislation alone would not fix the problem.
She wants cyber safety to be mandated as part of the Australian school curriculum.