Upgraded facilities at Ulladulla High School worth $27.5 million were officially opened by the Minister for Education Adrian Piccoli on Tuesday.
"The redevelopment of Ulladulla High School is one of the largest building projects undertaken in a NSW school in recent years," Mr Piccoli said.
In 2003 parents condemned the state government for allowing their children to learn in "Third World conditions".
At the time the school had more than 1250 students using facilities intended for a maximum of 880.
The redevelopment commenced in 2006 and was completed in three stages.
South Coast MP Shelley Hancock, a teacher at the school for 27 years, said the community should be proud of the long-fought campaign for the upgrade.
The project was jointly funded by the state and federal governments.