The organisation has given its backing, and the promise of £7.9 million, to the project, which will give a thorough overhaul to the gardens, considered by some to be the home of landscape design.
The proposals will also see the refurbishment of the Grade I-listed house, the creation of some new parking facilities, a home for a semi-permanent function marquee and a new café, possibly by Michael Hopkins.
While all agree that both the house and gardens are in urgent need of a thorough refurbishment, the plans have triggered major controversy.
Both local campaigners, made up of residents, and the Georgian Group have hit out at the plans. They are concerned that the car parking will ruin part of the historic walled gardens and that both the café and the marquee will ruin the setting of the house.
But Carole Souter, HLF director, said the scheme had her complete backing. 'Chiswick House and Gardens is a hugely popular and much-used local landmark,' she said.
'This major boost from the Heritage Lottery Fund will not only help safeguard the future of these beautiful gardens but will also attract many more visitors and volunteers to enjoy them,' she added.