The ruling paves the way for removing the site's restriction, which was put in place in 2017 due to texts accusing Turkey of links to terrorist organizations.
The state-run news agency, Anadolu, said the court's ruling was approved by a 10-vote majority.
"The Constitutional Court has ruled that our rights to Wikipedia have been violated in our case," said a lawyer representing the body, via a post on social media, Twitter.
Court representatives did not comment on the decision.
The site was blocked in April 2017 when a telecommunications observer cited a law that doest not allowed access on the grounds that it posed a threat to national security.