MacKenzie Bezos, who finalised her divorce to Amazon.com founder Jeff Bezos in April, has pledged to give at least half her fortune to charity.

She became one of the richest people in the world following her split from Mr Bezos, and has an estimated personal fortune of US$36.6 billion (S$50.4 billion), according to CNN.

She is one of the 19 new signatories of the Giving Pledge, according to a statement on the campaign's website on Tuesday (May 28).

The Giving Pledge is a commitment by some of the world's wealthiest people to give more than half of their assets to charity, either during their lifetimes or in their wills, and was founded by US billionaire investor Warren Buffett and Microsoft founder Bill Gates and his wife Melinda in 2010.

To date, the initiative has attracted the support of 204 signatories from 23 countries.

Mr Bezos, who has an estimated net worth of US$114 billion, has yet to sign on to the initiative.

His former wife is no stranger to philanthrophy, having funded cancer research through donations to the Fred Hutchinson Cancer Research Center, and Alzheimer's research through the Diagnostics Accelerator at the Alzheimer's Drug Discovery Foundation, according to the Giving Pledge statement.

In an excerpt from her Giving Pledge letter, Ms Bezos said: "In addition to whatever assets life has nurtured in me, I have a disproportionate amount of money to share.

"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."

Other new signatories of the Giving Pledge announced on Tuesday include cryptocurrency Coinbase's chief executive officer Brian Armstrong and WhatsApp co-founder Brian Acton.