Three Ghanaians and six other people were found guilty of taking part in a coup attempt three years prior, and they were all sentenced to death by hanging.
Since the ouster of post-independence leader Kwame Nkrumah in 1966, Ghana has not had a treason trial.
The six were arrested in 2021 while testing weapons in the capital, Accra, to allegedly topple the government.
The group entered a not guilty plea during a nationally publicised trial. The group included a gunsmith.
Attorneys for the defence announced that they would file an appeal with the Supreme Court.
Two military commanders and a senior police officer were among the three other individuals who received an acquittal.
The High Court in Accra had a large security presence throughout the sentencing on Wednesday.
The six were found guilty by the court of high treason and high treason conspiracy.
According to court documents, the guys were detained in possession of AK-47 weapons, homemade explosive devices, and firearms made in the area.
According to state prosecutors, the organisation intended to conduct demonstrations with the primary goal of overthrowing President Nana Akufo-Addo’s administration before the general elections in 2020.
The men’s testimony, which included testimonies and intercepted communications, was deemed persuasive by the court.
The prosecution’s attorney general, Godfred Yeboah Dame, called the court decision “significant”.
“The constitution of Ghana as the fundamental law of the country, which has sustained the stability of the nation, frowns seriously upon any attempt to overthrow a government and that is why that offence [treason] is punishable by death,” stated Mr. Dame.
When Ghana reverted to democratic rule in 1992, the country had last carried out an execution.
Legislators decided to replace the death penalty with a life sentence for non-violent crimes last year.