The government proposed the plan in November 2015 and it was approved by parliament in May but until Thursday there had been no official start date for the change.
Under the plan, 17-year-olds will be able to drive as long as they are accompanied by an experienced driver. The required age for beginning a driver's education course will also be lowered by one year, allowing teens to start driving school when they reach the age of 16 years and nine months.
Not until a person turns 18 can they drive unaccompanied, just as the rules are today.
Business Minister Troels Lund Poulsen championed the change when it was first proposed last year.
“It will allow for better accessibility in rural areas, and if mum or dad are sitting next to them, they will be confident in driving with an adult they trust,” Poulsen said at the time.
Lowering Denmark's legal driving age has been brought up several times before but had always failed to gain parliamentary approval before the vote went through in May of this year.
The Safe Traffic Council backed the initiative, saying it would "ensure that youths get more experience driving in traffic so they are better prepared to drive safely when they turn 18".
The programme is a three-year trial, after which it will either be made permanent or amended.