The attack, which took place on October 23 at a Greek Orthodox church in Karak, left at least nine people dead and 34 others injured. The victims were attending a Christian funeral when the shooting occurred.
Jordan's Armed Forces said in a statement on Sunday that the three men had been convicted of committing "terrorist acts", possessing weapons, "promoting the ideas of a terrorist organisation" and "conspiracy to commit terrorist acts", the BBC reported.
According to media reports, the accused comprise two Jordanian brothers and their brother-in-law. They allegedly fled the scene following the attack and were arrested a few days later after a shootout at an abandoned house.
The identities of the three men have not been publicly disclosed.
Karak is home to a significant Christian community in Jordan, a predominantly Muslim country.
The motive behind the attack and why the church was targeted remain uncler