Homes and businesses will have a legal right to demand high-speed broadband by 2020 under new regulations to help the 1.1 million premises who cannot access decent speeds.
The Government confirmed that everyone in the UK will have access to speeds of at least 10 Mbps under a regulatory Universal Service Obligation (USO), rejecting a voluntary proposal from network provider BT to improve speeds.
Under the plan, broadband providers will face a legal requirement to provide high-speed broadband to anyone requesting it, subject to a cost threshold.
Ofcom has said 10 Mbps is needed to meet the requirements of an average family.
The Government said it believed that only a regulatory USO offered sufficient certainty and the legal enforceability required to ensure high-speed broadband access for the whole of the UK by 2020.
It said it welcomed BT's "continued investment to deliver broadband to all parts of the UK".
Regulator Ofcom said this month that 4% of UK premises, or around 1.1 million, could not access broadband speeds of at least 10 Mbps.
Britain also lags behind most of Europe in providing fibre to the home which guarantees the fastest speeds available.
Culture Secretary Karen Bradley said: "We are grateful to BT for their proposal but have decided that only a regulatory approach will make high-speed broadband a reality for everyone in the UK, regardless of where they live or work.
"This is all part of our work on ensuring that Britain's telecoms infrastructure is fit for the future and will continue to deliver the connectivity that consumers need in the digital age."
Alex Neill, Which? managing director of home products and services, said: "This decision is welcome news, as consumers around the country simply want to know they will be able to access a broadband service.
"The Government must now move quickly to ensure consumers get these promised speeds by 2020 and closely monitor the programme to ensure it can keep pace with changing technology."