Students will benefit from a new sixth form centre and an art, design and technology building at St Benedict's School .
The school in Eaton Rise , Ealing, has received planning permission from Ealing Council to go ahead with the two new building projects on the site in Montpelier Avenue.
Architects van Heyningen & Haward submitted the designs, as well as one for a purpose-built extension to the junior school, creating a single building for early years and juniors.
The total cost will be about £12 million.
Work has already begun on the sixth form centre with the contractors Jerram Falkus to make the new space for relaxing, socialising and studying.
There will also be new classrooms for pre-preps two and three, a new reception and office areas.
The facilities should be ready for use by the end of 2015.
Landscaping around the new buildings will provide an improved whole school entrance, improved external play areas, a new nursery entrance and a relocated sixth form entrance.
Headmaster Chris Cleugh said: “These projects are hugely exciting and will ensure the school offers the very best accommodation for teaching and learning.
"The decision demonstrates the commitment of the governors to lead a school that will continue to flourish in the years ahead.”
