The Giving Pledge, an initiative created by Bill and Melinda Gates and Warren Buffett that encourages the world's richest people to vow to donate half of their wealth to charity, announced MacKenzie Bezos was one of 19 new individuals and couples to sign the commitment Tuesday morning. The total number of givers in the philanthropy group has climbed to 204 since the billionaires started it back in 2010.
Buffett, the chairman and CEO of Berkshire Hathaway, said he was "thrilled" to welcome the new group of signatories which includes Tegan and Brian Acton, Stewart and Sandy Bainum, Ben Delo and Brian Armstrong, among others.
"The generosity of this group is a reflection of the inspiration we take from the many millions of people who work quietly and effectively to create a better world for others, often at great personal sacrifice," Buffett, 88, said in an online statement.
MacKenzie Bezos, who became the third-richest woman in the world this year, according to Forbes, is an author and executive director of the anti-bullying organization Bystander Revolution.
The Giving Pledge boasted about MacKenzie Bezos' philanthropic efforts over the years, specifically her donations to cancer research, creation of college scholarships, support for marriage equality and assistance finding transitional housing for homeless families.
"We each come by the gifts we have to offer by an infinite series of influences and lucky breaks we can never fully understand. In addition to whatever assets life has nurtured in me, I have a disproportionate amount of money to share."
In a statement on the philanthropy group's website, the 49-year-old Seattle resident said she plans to maintain a "thoughtful" approach to philanthropy.
"We each come by the gifts we have to offer by an infinite series of influences and lucky breaks we can never fully understand. In addition to whatever assets life has nurtured in me, I have a disproportionate amount of money to share," MacKenzie Bezos wrote. "It will take time and effort and care. But I won’t wait. And I will keep at it until the safe is empty."
MacKenzie Bezos hopes other wealthy individuals will follow suit and encouraged those who don't currently have money to spend to consider giving back in other ways.
"I have no doubt that tremendous value comes when people act quickly on the impulse to give. No drive has more positive ripple effects than the desire to be of service. There are lots of resources each of us can pull from our safes to share with others — time, attention, knowledge, patience, creativity, talent, effort, humor, compassion," she added.
Jeff Bezos and MacKenzie Bezos confirmed they “finished the process of dissolving” their 25-year marriage in April. When they first announced their separation, more than $137 billion was on the line.
In an April tweet, MacKenzie Bezos said she gave her former husband all of her interests in the Washington Post and Blue Origin, as well as 75 percent of their Amazon stock. She also gave him voting control of her Amazon shares “to support his continued contributions with the team of these incredible companies.”
Fox Business' Megan Henney contributed to this report.