Wang Xiaoning was freed early on Friday morning, his wife, Yu Ling, told the BBC by telephone.
Mr Wang, who was detained in 2002, served his 10-year sentence in a Beijing jail.
Yahoo drew widespread criticism for providing information linking him to emails and political writings.
Ms Yu said her husband was in "good health and fine spirits" but was not allowed to give media interviews under the conditions of his release.
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Dissident convicted on Yahoo! data released in China
Yahoo! and other Western businesses can say "it's just business" but there are human costs to their actions. A ten year prison sentence in China because a company turned over information is serious stuff. BBC: