He was jailed for five years and eight months after pleading guilty to obtaining and disseminating classified defence information.
His sentence included a non-parole period of two years and three months, meaning the 61-year-old will remain imprisoned until at least August 2026.
Justice Belinda Baker rejected the appeal, handing down her judgment in under a minute in the ACT Court of Appeal, which operates as part of the Supreme Court, on Wednesday in front of McBride.
The reasons for her judgment will be published later.
His legal team had already flagged an appeal to the High Court if the decision didn't go their way.
McBride took 235 documents, 207 of which were classified as secret, and shared them with journalists.
The documents led to a series of reports that uncovered allegations Australian special forces soldiers committed war crimes in Afghanistan.
A subsequent inquiry found credible information about 23 incidents of potential war crimes, which involved the killing of 39 Afghans between 2005 and 2016.
At the time of his sentencing, ACT Justice David Mossop said the punishment reflected some concessions, such as McBride's early plea and mental health, as well as the need to deter people from leaking classified information.
McBride's lawyer, Eddie Lloyd, argued his sentence was too severe and that not enough weight was given to his guilty plea.
Human rights advocates have called for the Commonwealth to drop the prosecution and for McBride to be freed, saying his imprisonment will deter whistleblowing from coming forward.
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