Clark County Judge Linda Marie Bell denied Simpson's petition for a new trial in a 101-page ruling, the Las Vegas Sun reported. Bell had heard arguments from Simpson's attorneys during a five-day hearing in May.
Bell wrote Simpson failed to show his counsel was ineffective, deficient or had any material conflict of interest in representing him at trial or in his appeals. The judge said he also failed to establish prosecutors withheld evidence that would have helped clear him.
"Given the overwhelming amount of evidence, neither the errors in this case, nor the errors collectively, cause this court to question the validity of Mr. Simpson's conviction," Bell wrote.
"We're shocked and disappointed," Simpson attorney Patricia Palm told the newspaper upon learning of the ruling, which she said she had not read in full.
Simpson is serving nine to 33 years in prison after being convicted in 2008 for the armed robbery of two sports memorabilia dealers he claimed had items that belonged to him.
Simpson's stellar football career and subsequent work in the film industry have been eclipsed by his run-ins with the law, most notably his acquittal in the 1994 slaying of his ex-wife and her boyfriend.