Justin Stein was found guilty of murder in June, despite his claims it was the girl's mother Kallista Mutten - with whom he was in a relationship - who shot the nine-year-old.
The 33-year-old was sentenced in the NSW Supreme Court on Monday to the maximum sentence of life in prison without parole.
Police located Charlise's body on January 18, 2022, near the Colo River, northwest of Sydney, with gunshot wounds to her face and lower back.
In handing down the sentence, Justice Helen Wilson said Stein likely shot the girl once in the back while she was trying to flee, before approaching her and firing another shot directly into her head.
"This was a shockingly callous crime," Ms Wilson said.
"The offender approached Charlise and discharged the second shot at close range.
"It was not survivable and was not intended to be."
Justice Wilson said during the trial she had witnessed Stein pretending to cry as he gave a "wholly false account" of Charlise's death.
"His voice began to shake and then to break, he reached for a tissue and dabbed at his eyes," the judgen said.
"I could see very clearly that despite the offender's presentation of distress, he was completely dry-eyed and did not shed a single tear."
Justice Wilson told the court Stein's evidence could have been called "theatre" if it were not so serious, adding it pointed to his "complete lack of remorse".
A community grieved for Charlise Mutten, whose body was found in a barrel dumped in a river. (Regi Varghese/AAP PHOTOS)
Crown prosecutor Ken McKay SC told the court during a sentence hearing on Friday that due to the extreme nature of the crime, the only appropriate sentence for Stein was life in prison.
"He went to great lengths to avoid being held responsible for his actions," Mr McKay said.
Stein's lawyer, Carolyn Davenport SC, said it would be "very cruel and unusual punishment" to send a man of Stein's age to prison for the rest of his life.
"There was no motive that we know of," she said.
Charlise had been visiting her mother and Stein for Christmas from the Gold Coast, where she lived with her grandparents.
She spent the night of January 11 alone with Stein at a property in the Blue Mountains, while her mother stayed at a caravan about a 90-minute drive away.
Charlise's mother Kallista Mutten was in a relationship with Stein. (Bianca De Marchi/AAP PHOTOS)
Toxicology results revealed Charlise had traces in her body of the anti-psychotic drug Seroquel, for which Stein had a prescription to treat schizophrenia.
An adult dose of the drug would have a profound sedating effect on a child, the court heard.
The same day Charlise's body was found, investigators charged Stein with her murder after using location data from his phone to pinpoint where the barrel was dropped.
He would later admit dumping the body but claimed he panicked after discovering it on the back of his ute.
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