Kelly's appeal to reduce his 13-and-a-half year sentence for kidnapping Cleo Smith was denied by the WA Court of Appeal.

The three judges of the appeal court upheld the original sentence, rejecting Kelly's appeal.

Judges Robert Mazza and Stephen Hall supported the 13.5-year sentence, stating it reflected the severity of Kelly's crime.

Kelly, who pleaded guilty to the abduction, will be eligible for parole after serving 11 years and six months of his sentence.

Cleo Smith was abducted from her family's tent at the Blowholes campsite in Western Australia on October 16, 2021.

Terence Darrell Kelly held Cleo captive for 18 days before she was rescued in a police raid.

Cleo was found alone in a room at a property in Carnarvon on November 3, 2021, after being missing for 18 days.

During the abduction, it was revealed that Kelly was heavily under the influence of methamphetamine.

Judge Julie Wager concluded that Kelly initially intended to steal valuables but chose to kidnap Cleo due to his drug state.

The court emphasized that while the sentence was severe, it was justified given the serious nature of the offense.

WA Court of Appeal President Michael Buss found the sentence excessive, but this view was not shared by the other judges.

During sentencing in April 2023, Judge Wager described the trauma experienced by Cleo and her family as 'immeasurable'.