Charities could be fined tens of thousands of pounds if they fail to comply with new rules introduced this week to crack down on nuisance requests for donations.
The Fundraising Preference Service (FPS) will allow members of the public to say they want to stop a specified charity or charities contacting them directly by phone, email, text or post when it launches on Thursday.
Should a charity fail to comply with a person's wishes it may be reported to the Information Commissioner by the Fundraising Regulator.
The head of the watchdog said some charities have proven to be "laggards" in reforming their ways despite several high-profile and tragic cases exposing "extremely aggressive" practices in recent years.
Writing in the Daily Telegraph, Lord Grade said: "These stories rightly shocked Britain, and our trust in the charity sector has been sorely tested.
"It should be no surprise, therefore, that they have led to significant changes to the regulations governing fundraising in this country, designed both to restore that trust and to ensure that such terrible practices are never again tolerated."
In 2015 an outcry followed the case of 92-year-old Olive Cooke, one of Britain's oldest and longest-serving poppy sellers, who killed herself after receiving up to 267 letters a month as well as regular phone calls from fundraisers.
Lord Grade said the year had been an "annus horribilis" for Britain's charities, when some were exposed for prioritising raising as much money as possible without regard for the donors being targeted.
The former chairman of BBC and ITV said: "From this Thursday you will have the power to control the flow of communications that you receive from charities thanks to the Fundraising Preference Service.
"Developed and operated by the Fundraising Regulator, which I chair, it will enable you to block direct marketing communications from particular charities.
"In practice, this will mean that you will be able to go online or pick up a phone and name charities from which you no longer want to receive post, phone, text or email marketing communications."
Charities reported to the regulator will be issued with suppression orders giving them 28 days to stop contacting the complainant with unsolicited messages.
Should they continue, the charities could be reported to the Information Commissioner's Office, which has the power to prosecute under the Data Protection Act 1998 and issue fines if there has been a breach.