The five year deal could be extended up to 20 years and be worth £190m.
Willmott Dixon will deliver repairs to more than 20,000 Affinity Sutton homes across London and the South East.
Ian Morrison, Head of Property Services (Compliance) for Affinity Sutton, said: “Affinity Sutton has always been at the forefront of developing repairs partnerships and we are delighted to appoint Wilmott Dixon as our new repairs and maintenance contractor in this groundbreaking deal.”
Willmott Dixon Partnerships Managing Director, Mick Williamson, said: “We are delighted to be joining forces with Affinity Sutton to deliver significant cost savings alongside excellent service.
“We have a strong ethos of giving back to the community and will be offering training programmes and energy-saving initiatives to Affinity Sutton residents.
“We will also be providing employment opportunities via our Opening Doors work placement programme in conjunction with local schools.”