MacKenzie Scott, Amazon boss Jeff Bezos’s ex-wife, says that she has given $1.7bn (£1.3bn) to charity to date.
She has made donations to historically black US colleges, climate change groups and health organisations.
Ms Scott posted about the gifts on social media, also saying that she has changed her surname from Bezos.
She is the second-richest woman in the world, with a fortune of more than $62bn, according to Forbes.
She and Mr Bezos divorced last year.
The novelist, who married Mr Bezos a year before he founded Amazon and was one of the firm’s first employees, received a 4% stake after the split.
Shortly after announcing the divorce, Ms Scott signed the Giving Pledge, joining a campaign founded by billionaire investor Warren Buffett and ex-Microsoft boss Bill Gates and his wife Melinda. It commits the wealthy to give away the majority of their fortunes to charity.
Ms Scott said she had “watched the first half of 2020 with a mixture of heartbreak and horror” and was providing an update on the donations to draw attention to the causes during the coronavirus pandemic.
“My own reflection after recent events revealed a dividend of privilege I’d been overlooking: the attention I can call to organizations and leaders driving change,” she wrote in a blog post on Medium.