Badawi, now 38, was arrested in 2012 for criticising the Saudi religious police in an online forum and was sentenced to 10 years in jail and 1000 lashes for insulting Islam.
"After 10 years in prison Raif is free!" his wife, Ensaf Haider, said on Twitter without giving details.
Haider lives in Canada with the couple's three children.
Badawi was released on Friday after the expiration of his sentence, non-governmental watchdog AlQST for Human Rights also said on Twitter.
He remains under a 10-year travel ban, added the group that advocates for human rights in Saudi Arabia.
So far, there has been no official comment from Saudi authorities.
He completed his 10-year term on February 28, rights activists said.
His imprisonment and public lashing provoked an international outcry.
In June 2015, Saudi Arabia's top court upheld the sentence against Badawi.
In October that year, Badawi was awarded the European Parliament's Sakharov Prize for Freedom of Thought.
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