A panel of judges in the NSW Court of Criminal Appeal dismissed Dawson's appeal against his murder conviction on Thursday.
Dawson's lawyers had argued the guilty verdict against him was unreasonable.
Barrister Belinda Rigg SC told the appeal court in May there was not enough evidence to prove beyond reasonable doubt he murdered his wife Lynette Dawson in 1982.
But the state's highest court upheld Dawson's convictions, granting him leave but then dismissing his appeal.
The ex-teacher and former rugby league player was convicted in August 2022 of murdering his wife Lynette Dawson so he could pursue a relationship with a teenage girl, who was one of his students.
He has also been convicted of a historical charge of carnal knowledge as a teacher of a girl over 10 and under 17.
Dawson swore repeatedly when a judge delivered that guilty verdict in June 2023, which he also plans to appeal.
It added another year to the period before which Dawson will be eligible for parole.
His first possible release date will be in August 2041, when he will be 93.
Dawson's full 24-year sentence for murdering his wife expires in 2046.
Her body has never been found and laws preventing parole in those circumstances mean the 75-year-old will likely spend the remainder of his life in prison.
Both guilty verdicts came after judge-alone trials as Dawson's crimes attracted significant publicity before he was charged.
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