In a 15-year joint venture with Metropolitan Living, Countryside will deliver nearly 2,500 homes at 17 sites across the Clapham Park Estate.
The £800m phase two works are expected to commence in Spring 2022 with first completions expected in 2024.
This phase will provide nearly 2,400 homes, non-residential builds, public realm and infrastructure.
Just over half the new homes will be for affordable tenures. The homes will have green and solar roofs and be supplied by a district heating system.
Since the transfer of Clapham Park from the London Borough of Lambeth, Metropolitan has completed over 1,500 new homes and refurbishments.
With the first 50 homes under that permission currently under construction, the joint venture will take forward the remainder.
On completion, Clapham Park, which spans 36 hectares and is nestled between three local centres, Clapham, Brixton and Streatham Hill, will have a total of over 4,000 homes.
Iain McPherson, Group Chief Executive, Countryside, said: “We are thrilled to form this joint venture partnership with MTVH.
“As a partnerships-based business, our commitment to delivering high-quality, sustainable mixed-tenure communities is unwavering. With shared values, I have no doubt this joint venture will bring to life the ambitious vision for Clapham Park, delivering a vibrant and inclusive series of neighbourhoods with safe, secure streets and ample public and private green space.”