Some 137 people were executed in the Gulf monarchy in 2015 convicted of different offences.
In response to this news, Philip Luther, Director of Amnesty International's Middle East and North Africa Programme, said: "This is a grim watershed. With its 100th execution this year, Saudi Arabia is speeding along in its dogged use of a cruel and inhuman punishment, mindless of justice and human rights.
The kingdom, which applies a strict Wahhabi interpretation of Islamic law, has repeatedly rejected calls to end the death penalty, saying the punishment is aimed at deterring would-be offenders.
Luther added, "Many of those executed have been convicted after deeply unfair trials, as a result of flaws in the justice system. The Saudi Arabian authorities must immediately establish an official moratorium on executions and abolish the death penalty once and for all."