More than 30,000 premises will be in the Sedgefield constituency.
The company has already covered 1 million premises across the UK with its full fibre network and it is in the process of investing another £1 billion this year, which should enable it to cover an additional 1 million UK premises.
The investment will also enable the provider to move into other areas of Newton Aycliffe including, Trimdon, Trimdon Grange, Fishburn, Chilton, Ferryhill and Cornforth.
Rajiv Datta, CEO of nexfibre, said, "We are committed to delivering high quality full-fibre connectivity to communities and business across the UK, including in Sedgefield and the wider county of Durham. By boosting access to broadband, we are enabling access to the tools needed to participate and thrive in a modern, digital society and stoking growth in the local economy."
Paul Howell, MP for Sedgefield, said, "The investment nexfibre is making in Newton Aycliffe, Trimdon, Trimdon Grange, Fishburn, Sedgefield, Chilton, Ferryhill, and Cornforth will create jobs, drive economic growth and help provide better services for people locally. This Conservative government has made boosting access to fibre broadband a priority and we are delivering that for local people and communities here in the North East and across the country.
"I welcome the work nexfibre is doing to increase access to quality broadband and provide the national scale competition that will drive the innovation and progress the UK needs in the fibre market."