The rankings, released on Tuesday, showed that Danish students' results in mathematics, reading and science are now at or above the OECD average for the first time ever.
Among OECD countries, Denmark was ranked number seven in mathematics, number 15 in science and number 15 in reading.
Danish students' performance was good enough for an overall 21st place ranking in the Pisa study, making it the second-best Nordic nation. Finland placed fifth, while Norway was 24th and Sweden was 28th.
Singapore, Japan and Estonia topped the rankings, which tests 15-year-olds in 72 countries and territories.
Newly-appointed Education Minister Merete Riisager said Denmark's teachers deserved a pat on the back for such marked improvements.
“It is a really good job by math teachers in particular, who have managed to significantly improve the students,” she said.
But Riisager declined to give credit for Denmark's improvements to the school reform that was implemented in 2014.
“We cannot conclude anything about the school reform with the Pisa results, but they help paint a picture of our schools and how things are going for 15-year-old students in math, science and reading,” Riisager, an outspoken critic of the recent school reform, said.
The Pisa results also showed that Danish students' socio-economic background plays a lesser role than in previous editions in how well students perform in school.
The results also revealed, however, that Denmark is well below the OECD average when it comes to the scholarly performance of immigrant students.
More information on Denmark's Pisa results can be seen here: