Andrew Swallow, 32, was placed on the NSW Child Protection Register in 2007 after being convicted of underage sex offences a year earlier.

The conditions of the register require Swallow to promptly report any number of changes in his situation to police, including, but not limited to, his address, phone number, employment, social interactions, use of mobile phones, memberships of clubs, distinguishing features including tattoos, travel arrangements, and use of social media platforms or internet chat rooms, etc.

Court documents said police were investigating an unrelated matter last year when they obtained two images of Swallow that had been uploaded to a Grindr profile set up in his name.

Both images presented Swallow in sexual positions: the first showed him standing with the front of his pants pulled down and his hand holding his groin area, while the second showed him laying naked on a bed holding his erect penis.

Swallow's face was clearly visible in both pictures, as was a tattoo of two red lips he'd recently had etched on his hip.

Police spoke to him about the profile and images in November last year, at which time Swallow said he'd created the account in March that year following his release from jail, but had deleted it about less than a month later after meeting his current girlfriend.

"It was just a joke," he said.

When asked why he hadn't reported it to police, Swallow replied "I didn't think about it".

He was charged with failing to comply with his reporting obligations, to which he pleaded guilty in Wollongong Local Court on Tuesday.

Magistrate Jillian Kiely warned Swallow he was facing jail time for the offence, noting he'd had multiple warnings for past breaches.

Court documents reveals Swallow failed to report a change of address in June 2014, a change in his phone number and vehicle registration in November 2014 and a new tattoo and further change of address in June 2015.

A background report will be prepared ahead of Swallow's sentencing on March 3.

He remains on conditional bail.