A witness said they were shot dead in a square in the southern city of Abha – not beheaded as is usually the case.
The men were sentenced to death in 2009 after being found guilty of organising a criminal group, armed robbery and breaking into jewellery shops.
On Tuesday, a group of UN independent experts urged the Saudi authorities not to proceed with the executions.
They expressed concern at allegations that the charges against Sarhan al-Mashaikh, Saeed al-Zahrani, Ali al-Shahri, Nasser al-Qahtani, Saeed al-Shahrani, Abdul Aziz al-Amri and Ali al-Qahtani were fabricated and that they were convicted following unfair trials.
“In countries that have not abolished the death penalty, capital punishment may be imposed only following a trial that complied with fair trial and due process safeguards,” said Christof Heyns, the special rapporteur on extrajudicial, summary or arbitrary executions.
The special rapporteur on torture, Juan Mendez, added: “Also of grave concern, are allegations that the seven individuals were subjected to torture and other ill-treatment in detention and were forced to sign confessions.”
If confirmed, these would represent breaches of Saudi Arabia’s international obligations under international law, Mr Mendez stressed.
Amnesty International described the executions as “sheer brutality” and said two of the men had been juveniles at the time of their alleged crimes.
“It is a bloody day when a government executes seven people on the grounds of ‘confessions’ obtained under torture, submitted at a trial where they had no legal representation or recourse to appeal,” said Philip Luther, the human rights group’s Middle East and North Africa director.
The interior ministry statement published by the official SPA news agency on Wednesday did not mention how the men were executed, stating only that their death sentences had been implemented in Abha.
It had been expected that the men would be beheaded, but unconfirmed reports over the weekend said the authorities had been forced to resort to using firing squads because of a shortage of swordsmen.
In 2012, at least 69 people were executed in Saudi Arabia.