The green light has been given for the first new grammar school in 50 years.
Approval for the 450-pupil school - an extension of an existing grammar in Kent - was confirmed by Education Secretary Nicky Morgan this morning.
In a written statement, she insisted the decision was not a change in the government's position on selective schools.
Labour passed laws in 1998 banning the creation of new grammars - which are selective state schools - but existing schools are allowed to expand if there is sufficient demand.
The Sevenoaks school is not covered by the ban because it is officially an annexe of Weald of Kent Grammar School in Tonbridge.
Mrs Morgan's statement said: "I am satisfied that this proposal represents a genuine expansion of the existing school and that there will be integration between the two sites in terms of leadership, management, governance, admissions and curriculum.
"I am also satisfied that the excellent quality of learning currently delivered will be replicated across the newly-expanded school."
She added: "My decision in this case has been taken on the basis of the proposal from the Weald of Kent, in line with legislation and criteria determining what constitutes an expansion.
"It does not reflect a change in this Government's position on selective schools.
"Rather it reaffirms our view that all good schools should be able to expand, a policy which is vital to meet the significant increase in demand for pupil places in coming years."
The new site is expected to open to pupils in September 2017.