The national award by the Scripps Howard Foundation recognized the newspaper's six-part "Locked Out" series that detailed secrecy in local government.
The award carries a $2,500 prize, which the Star-Bulletin donated to a new First Amendment coalition being formed by local community groups and news organizations to fight for open government.
Writers of the series, which appeared Sept. 2 to 7, were Ian Lind, Richard Borreca, Pat Omandam, Gordon Pang and Jim Witty.
Other key contributors included city editor Lucy Young-Oda, night editor Stirling Morita, graphics editor Dan Woods, chief artist Kevin Hand and assistant managing editors Frank Bridgewater and Michael Rovner.
Judges were Louis D. Boccardi, president and chief executive officer of the Associated Press; Sandra Mims Rowe, editor of the Oregonian, and Loren Ghiglione, James M. Cox Jr. Professor of Journalism at Emory University.
They said: "A year in the making, the Honolulu Star-Bulletin's six-day special report on the troubled state of freedom of information in Hawaii sounded the alarm, explained what was at stake and led the way to critical and much-needed reforms.
"At the outset of the series, managing editor David Shapiro wrote, 'It's becoming increasingly difficult for citizens in Hawaii to find out what their government is doing.' Thanks to this series, that is markedly less true than it was."
Lind will accept the award at a banquet in Cincinnati March 26.