Sajada Ansari, a shepherd, was convicted of robbing his Saudi boss as he slept and beating him to death with a hammer, the ministry said in a statement carried by the official Saudi Press Agency.
The other convict, Saudi Mater al-Rowaeeli, was condemned for shooting dead his ex-wife and two of their children.
Both executions were carried out in the kingdom’s north.
They bring to 65 the number of beheadings by the sword this year in Saudi Arabia, a surge that compares with 87 death sentences in all of 2014, according to AFP tallies.
Drug trafficking, rape, murder, apostasy and armed robbery are all punishable by death under the Islamic sharia law.
Amnesty International’s 2014 global report on the death penalty ranks Saudi Arabia among the top five executioners in the world.
The interior ministry has cited deterrence as a reason for carrying out the punishment and says executing murderers aims “to maintain security and realise justice”. -AFP