Nikeisha Webb-Hardy, deputy head of Gesher for the past year, has been made joint head, responsible for secondary provision at the independent special school in Pinner.
She will join co-head Tamaryn Yartu, who will oversee the primary section of the school for children with mild to moderate learning differences.
In September last year, Gesher moved into new premises on the site of the now- closed Moriah Jewish Day School, adding secondary-age classes to its primary provision.
The school, which has 51 students, plans to grow to 100 over the next five years.