The businessman announced in The Sunday Telegraph that he has signed up to the Giving Pledge, a promise by the world's wealthiest individuals and families to dedicate the majority of their wealth to philanthropy.
With an estimated fortune of £1.1 billion, according to the Sunday Times Rich List, Lord Ashcroft said he will leave at least half of his assets to a charitable foundation in his name.
"When I die, I have decided to leave the majority of my assets to a charitable foundation in my name," he wrote in The Sunday Telegraph.
"I have never been a great believer in inherited wealth. After my death, my family will be trustees of the foundation so that they will be able to enjoy making donations to worthy causes in my name."
The Giving Pledge, which is a moral commitment and not a legal contract, was set up by Microsoft founder Bill Gates and his wife Melinda Gates, and investor Warren Buffett. Lord Ashcroft will be added to the list of "pledgers" on Tuesday.
He said that his family "wholeheartedly" support his decision. However, he said he will provide for his family, believing it "a little harsh" to leave them with nothing.
Alongside donating tens of thousands of pounds to charitable causes, Lord Ashcroft set up Crimestoppers 25 years ago and helped to open a gallery of the world's largest collection of Victoria Crosses and George Crosses at the Imperial War Museum to champion bravery.
He said the roots for his philanthropic work grew from a work ethic and social responsibility instilled in him by his parents.