The "Giving Pledge", founded in 2010 by Buffet along with Bill and Melinda Gates, has drawn 204 billionaire pledgers, including WhatsApp Co-founder Brian Acton, Tesla CEO Elon Musk and Facebook founder Mark Zuckerberg and his wife, Priscilla Chan, CBS News reported on Tuesday.
"My approach to philanthropy will continue to be thoughtful. It will take time and effort and care. But I won't wait. And I will keep at it until the safe is empty," 48- year-old MacKenzie wrote in an open letter recently.
The Bezos couple finalised their divorce in April in what was reported as the biggest divorce settlement in history entitling MacKenzie Bezos to Amazon stocks worth around $36 billion to $37 billion.
Bezos also gave her ex-husband all of her interests in the Washington Post and Blue Origin, and 75 per cent of their collective Amazon stock along with the voting control of her shares to support his continued contributions to the teams.
Applauding his ex-wife on her donation decision, 55-year-old Jeff Bezos wrote, "MacKenzie is going to be amazing and thoughtful and effective at philanthropy, and I'm proud of her. Her letter is so beautiful. Go get 'em MacKenzie," on Twitter.
The former couple announced their split in January after 25 years or marriage.
According to Forbes, Jeff Bezos is the richest man in the world with an estimated fortune of $110 billion, ahead of Microsoft Co-founder Bill Gates and Berkshire Hathaway chairman Warren Buffett, the report added.
( With inputs from IANS )