The executions brought to 127 the number this year in Saudi Arabia, compared with 87 in 2014, according to AFP tallies compiled from interior ministry statements.
Saudi Nawaf al-Otaibi was executed in the western city of Taif after being convicted of shooting dead his father in a dispute, the interior ministry said.
Fellow Saudis Bandar al-Ghathim and Abdulaziz Mohammed al-Zahrani were executed in the country's southwest for murder, the ministry said in statements carried by state news agency SPA.
Under Saudi Arabia's strict legal practices, murder, armed robbery, rape, drug trafficking and apostasy are all punishable by death.
Also Read
Most people sentenced to death in Saudi Arabia are beheaded, but sometimes firing squads are used.
Amnesty International yesterday criticised Saudi Arabia's "deeply flawed judicial system" as it issued a new report on the rising number of executions.
The London-based group criticised trials it said "blatantly flout international standards", citing secret hearings, denying defendants access to lawyers and convictions based on confessions "obtained under torture".
Amnesty says Saudi Arabia is one of the world's most prolific executioners, along with China, Iran, Iraq and the US.