NORTHWOOD School in Potter Street is to be rebuilt, to increase its capacity to 900 pupils.
The new school is to open in 2016 at an estimated cost of £28m, with Hillingdon providing £21.6m and central government the balance.
The rebuild complements athe council's Primary School Building Programme of £150 million.
Cllr David Simmonds, council deputy leader, said demand for places would increase in future years.
“Providing quality school places for pupils near where they live is an absolute priority,” he added.
Work is also progressing on the borough’s primary school building programme - the largest of its kind in London - which will create 6,500 additional places.