Pte Sean Rooney, 24, was killed while on a peacekeeping mission, when the armoured vehicle he was travelling in came under fire on December 14 near the village of Al- Aqbiya, in southern Lebanon, where Hezbollah has a strong presence.
Ten days later, Mohammad Ayyad, a man suspected of shooting and killing the Irish soldier, was handed to authorities by Hezbollah.
The National approached Hezbollah for a statement, but a representative for the party said they had "no comment at the moment".
A spokesman for the militant group and political party had previously told Reuters that the man was a supporter of Hezbollah but not a member.
According to the military court's indictment, the five people charged "formed a criminal gang and implemented a criminal project".
"This is one important step towards justice and we continue to urge accountability for all perpetrators involved. Attacks on men and women serving the cause of peace are serious crimes and can never be tolerated. We look forward to justice for Private Rooney, his injured colleagues, and their families," a spokesperson for Unifil told The National.
The 30-page indictment, seen by AFP, accuses the individuals of "voluntary homicide", and all have been referred to the military court for trial.
The indictment said that the actions of detainee Mohammad Ayyad and the four others – who are still at large –are punishable by death under the Lebanese penal code.
Surveillance images from cameras near the scene of the attack show "clearly the patrol under attack from all sides, by armed men", according to the report.
"Some of them were heard saying 'We are from Hezbollah' and calling each other via walkie-talkies," the indictment added.
At least 320 soldiers serving with the United Nations Interim Force in Lebanon (Unifil) have lost their lives since the start of its mandate in 1978.
Unifil was created by the Security Council to confirm Israel's withdrawal from Lebanon and assist the Lebanese government in restoring its effective authority in the area.
The last time peacekeepers were killed in an attack was in 2007 when six international peacekeepers were hit by a bomb blast in southern Lebanon.