Terence Darrell Kelly appealed against his 13-and-a-half years' jail term for snatching the girl at the Blowholes campsite, about 70km north of Carnarvon in the early hours of October 16, 2021, as her parents slept.
Cleo was missing for 18 days before finally being found by police alone in a room at a property in Carnarvon on November 3.
Her kidnapping by the 37-year-old sparked one of the biggest police searches in WA history and made headlines worldwide.
Cleo Smith's kidnapping sparked one of the biggest police searches in WA history. (Richard Wainwright/AAP PHOTOS)
Sentencing Kelly in the District Court in April 2023, Chief Judge Julie Wager described the fear, distress and trauma caused to Cleo and her parents as "immeasurable".
"Eighteen days without contact or explanation, and with hours totally on her own and no access to the outside world, would have been very traumatic," the judge said.
Under his sentence Kelly, who pleaded guilty to taking Cleo, will be eligible for parole after serving 11 years and six months.
In February, his lawyers argued in the WA Court of Appeal that the sentence was manifestly excessive.
They disputed Judge Wager's finding that Kelly was significantly affected by methamphetamine when he abducted Cleo, and also argued the sentence did not place sufficient weight on his deprived, traumatic childhood and mental impairment.
The appeal judgment is due to be delivered on Monday.
