The 32-year-old one-time NSW Origin representative was on Wednesday spared a jail term when he appeared in Wollongong Local Court after pleading guilty to supplying 39 grams of cocaine at Cameron Park in 2018.

Instead, Magistrate Jillian Kiely placed Mullen on a three-year community corrections order, the equivalent of a good behaviour bond, and ordered he complete 300 hours of community service.

Ms Kiely noted Mullen's turnaround since a near fatal overdose in 2018 and his aspirations to become a role model for young rugby league players.

"Not only has he personally and professionally hit rock bottom, he almost died from an accidental overdose and now suffers from permanent hearing loss," Ms Kiely said during her sentencing remarks.

"That would have served as an extreme wake-up call."

Mullen pleaded guilty in December to supplying cocaine, after police surveillance captured him purchasing 39 grams of cocaine, which had a street value of $12,000, over four separate occasions in November, 2018. Defence lawyer Paul McGirr told the court Mullen's fall from grace was an "extremely sad situation".

"He was one of Newcastle's favourite sons," Mr McGirr said. "He now doesn't even want to return to the area."

He told the court Mullen was "shattered" by his offending, and it made him sick to think of the impact it had on his family.

The former halfback played 211 matches for the Knights after debuting in 2005, represented NSW in a State of Origin match and was once tipped to be the next Andrew Johns.

Instead, his career was cut short in 2017 when he received a four-year ban from ASADA after testing positive to anabolic steroid drostanolone, which prompted his downward spiral into cocaine abuse and ultimately led him to become involved in a major drug supply syndicate that was operating out of the Hunter. "Just ever since my career finished, I spiralled out of control and was taking cocaine on a daily basis just to get through the day, to suppress the demons, I suppose," Mullen told detectives. "And a lot of prescription drugs, stuff which led me to rehab ... well I did go through a dark stage, yeah."

Mullen started selling cocaine for $300 per gram to finance his heavy drug habit, which culminated in his parents finding him overdosed on their couch in the weeks before Christmas.

He subsequently entered a rehabilitation program and says he has been clean ever since. He was arrested in May, 2019, less than a month after moving to the Illawarra to live with his girlfriend, who is due to give birth to their first child next week. She supported him in court on Wednesday, along with his mother.

Mullen came under the attention of detectives after police began investigating his supplier in August, 2018.

Mullen later admitted to buying the 39 grams of cocaine in four separate transactions between November 23 and November 30.

He mainly sold to friends using encrypted apps and used code words to conceal the deals.

In arguing for Mullen to avoid jail, his lawyer told the court the former star hopes to begin playing professional football again next year.

"He still is keen to get back into rugby league, and at 32 years of age he has his work cut out for him," Mr McGirr said.

If that doesn't work out, Mr McGirr said Mullen aspired to become a role model and counsellor for trouble young rugby league players.

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