Operation Fuavai made 177 arrests between 23 December and 6 January, nearly 100 less than the previous year at the same time.
And the road toll for the entire year was four compared to 22 in 2018.
Acting Deputy Commissioner 'Atunaisa Taumoepeau said from the middle of last year, patrols had been boosted, particularly around the capital of Nuku'alofa.
"Our tactical response unit and all supporting units assist our general business area on the weekend and since then we see that the people are getting more used to that.
"They know the visibility of police in most areas, in public places, and also nightclubs and things like that. I think that was really helpful," he said.
Domestic violence cases high in holidays
However, while Deputy Commissioner Taumoepeau welcomed the general drop in arrests he acknowledged there were still too many.
Of the holiday arrests, 62 were related to domestic violence incidents.
Domestic violence was an ongoing issue in Tonga.
"It seems that the past eight to 10 years, domestic violence is part of our major operations within the police and it's consistent throughout the years as well.
"We try our best to get those numbers down. Sixty-two within two weeks is still a lot," he said.
Domestic violence cases might increase over the holidays because more alcohol was consumed.
A lot of work was being done with civil society organisations and other groups to help address the issue, he said.