It is now illegal to use a mobile phone while driving, or to use a car without a registration plate.
Children must also be seated when a vehicle is in motion, and they can no longer sit on the driver's lap.
Playing loud music, extreme tinting and the addition of blinking, colourful or distracting lights have also been prohibited.
The new laws will be published on the Crown Law website on Friday, with police beginning compliance checks that day.
The Ministry of Infrastructure says the laws will make Tonga's public roads safer.
It says 2018 was the deadliest year on the roads in 10 years, with a total of 21 deaths.
"The Traffic Act 2020 and the Roads Act 2020 have long been discussed and consulted on with the public and by the government during its passage through the legislative assembly," the Ministry of Infrastructure said.