Stephen Caldwell said he was happy with the significant reduction as it meant there had also been a corresponding reduction in the victims of crime.
In the year ending November, there were 2054 less offences reported than in 2016.
The capital of Nuku'alofa accounts for 70 percent of the nation's crime, but there was an 18 percent drop there.
Police said it was a busy year for them with major operations targeting alcohol related offending including those surrounding Rugby League World Cup celebrations, which resulted in 451 arrests, and Operation Safe Street which netted 788 arrests over the year.
Photo: SUPPLED Tonga police commissioner, Stephen Caldwell