MacKenzie Bezos says her divorce from ex-husband Jeff has been finalized in an agreement that will see him retain 75 per cent of their shares in Amazon, along with complete control of space travel company Blue Origin and influential newspaper the Washington Post.

In a tweet, Bezos said on Thursday that while she will retain one-quarter of the couple's stake in Amazon, the company they founded out of their garage in 1994, she will hand over all of the voting shares to Jeff "to support his continued contributions with the teams of these incredible companies."

The couple split earlier this year after more than 20 years of marriage, in a development that some thought could be one of the most expensive divorces in history, given that her ex-husband is the richest man on earth, worth roughly $150 billion US, according to Bloomberg, on top of her own net worth, which is also believed to be in the tens of billions.

According to regulatory filings, the Bezoses own 78,814,170 shares in Amazon, about 16 per cent of the company and worth just under $143 billion based on Thursday's trading price for the shares.

The deal means MacKenzie Bezos now owns almost 20 million shares or four per cent of the company, worth just under $36 billion.

Bezos says she will also hand over her interests in space travel company Blue Origin, and her ownership stake in the Washington Post.

"Grateful for the past as I look forward to what comes next," she said.