Ofcom has called on broadband providers to give customers better information about speeds before they commit to a contract.
The watchdog's revised Voluntary Code of Practice states that providers must give a minimum guaranteed speed to a potential customer at the point of sale.
If the customer's speed drops below the promised level, the provider must improve their performance within a month.
Otherwise, customers will be allowed to exit their contract without paying a penalty.
Ofcom has also called on broadband providers to give customers more realistic peak-time speed information before they sign up to a contract.
This, it said, would reflect the fact that broadband tends to be slower during those periods when more people are online and offer "an extra protection" to consumers.
The right to exit a contract will apply to people who have purchased their broadband in a bundle with landline and TV services.
As a result, customers will not be tied to another service they purchased at the same time as their broadband, should their connection speed fall below what was promised and they choose to cancel.
The new rules will also apply to all customers regardless of their broadband technology, ensuring users of copper cable and part or full-fibre are all equally protected.
Providers now have a year to make the necessary changes to their systems, before the rules come into place on March 1st 2019.
Lindsey Fussell, Consumer Group Director at Ofcom, said: "Broadband customers must know what they’re signing up to.
"These protections will close the gap between the broadband speeds people are sold, and what they actually receive."
Ms Fussell added that making it easier to exit a contract if companies fail to deliver will give people "extra confidence".
The announcement comes shortly ahead of the introduction of new rules regarding the advertising of broadband speeds.
From May 23rd 2018, the Advertising Standards Authority (ASA) will require broadband providers to ensure future speed claims in ads are based on average speeds at peak times.
Providers are currently allowed to advertise broadband speeds if they are available to ten per cent of their customers.
However, the ASA has been concerned for some time that this could potentially mislead people, with the majority of customers possibly not getting the speeds they expected.
Following a consultation by the Committees of Advertising Practice (CAP), the watchdog is therefore imposing new rules, which state that advertised speeds should be based on the download speed available to at least half of customers at peak times and described in the ads as "average".