The builder will renovate and modernise the Grade II listed 1941 building to enable better staff working
This will include upgrading the town hall and assembly hall and civic square.
Approved plans by architect Hawkins Brown focus on creating an inclusive and welcoming space while transforming the way the council operates and delivers services to residents of the borough.
In phase two developer Countryside will later redevelop parts of the large site for much-needed affordable housing and site landscaping.
Between 500 and 600 new homes will be provided across the town hall campus and Willow house sites, as part of the £150m investment plan.
Nick Oddy, managing director for ISG’s Agility business, added: “Following schemes to create the UK’s first Urban Cricket Centre, the Waltham Forest Feel Good Centre and Leyton Leisure Centre, we’re delighted to again be working with the council to deliver another project that will have a transformational impact on the local community.”