The ruling by Los Angeles Superior Court Judge Dzintra Janavs ordered the Internet Corporation for Assigned Names and Numbers (ICANN) to disclose contracts, travel records, minutes and other internal communications.
It came after a lawsuit asking for the disclosure by Karl Auerback, an ICANN board member.
ICANN is the four-year old internet governing organisation whose main function is to settle domain name disputes. Domain names are the addresses typed into a web browser to find a particular site.
The organisation has been criticised for being too secretive and powerful in its governance. US lawmakers held hearings on the matter in June, and have expressed favour in scaling back and opening up ICANN procedures.
The ruling came after Auerbach was refused access to internal decision making documents held by ICANN.
The organisation is the rare central body overseeing the internet, which has grown to become an international quilt of computers and networks with haphazard oversight, usually by individual governments.
ICANN was created to oversee the addresses used to access the internet and websites, in lieu of any governmental body taking on that role.
An ICANN spokeswoman said the organisation is reviewing the ruling for possible appeal.
