A Saudi court in September upheld a sentence of 10 years in prison as well as the flogging for Raef Badawi, who has been behind bars since June 2012.The 30-year-old received a first instalment of 50 lashes on Friday and is expected to have 20 weekly whipping sessions until his punishment is complete.
The United States, Amnesty International and Reporters without Borders (RSF) have denounced the flogging as a horrific form of punishment, saying Badawi was exercising his right to freedom of expression.
Sweden's Foreign Minister Margot Wallstrom joined the chorus of condemnation.
"Blogger Raef Badawi was flogged today in Saudi Arabia. This cruel attempt to silence modern forms of expression has to be stopped," she said on her official Twitter account.
Witnesses said that Badawi was flogged after the weekly Friday prayers near Al-Jafali mosque in the Red Sea city of Jeddah as a crowd of worshippers looked on.
He was driven to the site in a police car, and taken out of the vehicle as a government employee read out the charges against him to the crowd.
The blogger was made to stand with his back to onlookers as another man began flogging him, witnesses said, adding that Badawi did not make any sound or cry in pain.
People who had emerged from noon prayers watched in silence and were ordered by security forces not to take any pictures on their mobile phones.
London-based Amnesty International, citing witnesses, said the whole ordeal "lasted around 15 minutes" and that Badawi was shackled.
"The flogging of Raef Badawi is a vicious act of cruelty which is prohibited under international law," said Amnesty's Said Boumedouha, describing the blogger as a "prisoner of conscience".
"By ignoring international calls to cancel the flogging Saudi Arabia's authorities have demonstrated an abhorrent disregard for the most basic human rights principles."
Rights groups have also criticised Saudi Arabia, an absolute monarchy, for regularly beheading convicts under its strict version of Islamic sharia law.Rape, apostasy, murder, armed robbery and drug trafficking are all punishable by death.
Amnesty, echoing other rights groups, said Badawi's "only 'crime' was to exercise his right to freedom of expression by setting up a website for public discussion," and demanded his unconditional release.
The US had urged its ally Saudi Arabia to cancel the "brutal" lashing of Badawi.
Media watchdog RSF said the punishment was "barbaric" and noted it came after Saudi Arabia condemned the assault on French magazine Charlie Hebdo that left 12 people dead.
It said Badawi, who was also ordered to pay a fine of one million riyals ($267,000, 192,00 euros), had "just used his freedom of expression and information."
In February, RSF said that Gulf monarchies, fearful of unrest, had stepped up efforts to monitor and control the media, particularly online.
Saudi Arabia is on the group's "Enemies of the Internet" list.
In October three lawyers in Saudi Arabia were jailed for up to eight years and banned from using social media over tweets that undermined the judiciary, according to officials.
Badawi is the co-founder of the now-banned Saudi Liberal Network along with women's rights campaigner Suad al-Shammari, who was also accused of insulting Islam and arrested last October.
Shammari has said the charges against Badawi were levelled after the Saudi Liberal Network criticised clerics and the kingdom's notorious religious police, who have been accused of a heavy-handed enforcement of sharia law.
In July 2013, a court initially sentenced Badawi to more than seven years in jail and 600 lashes, but an appeals court overturned the ruling, sending the case back for retrial when he received a harsher sentence.
Amnesty said flogging is prohibited under international law while Reporters Without Borders slammed "Saudi Arabia's Friday of shame".