Bezos' bump to the top spot happened Monday when his net worth added about $1.4 billion after Amazon's stock rose 1.4%-Bezos owns almost 80 million shares worth.
Gates, 62, would have a net worth of more than $US150 billion if he'd held onto assets that he's given away, largely to the Bill & Melinda Gates Foundation.More news: HTC Vive Pro revealed alongside Vive Wireless Adaptor
Amazon's share price, and therefore Bezos' net worth, has jumped significantly since September. That is about 17 per cent of the online book-selling company that he founded in a Seattle garage in 1994.
Microsoft (MSFT) founder Bill Gates officially got the memo on Monday that he is no longer the richest person in the world.
Bezos also controls closely held space exploration business Blue Origin and The Washington Post. He first crossed the $100 billion net worth mark in November at the start of the holiday shopping season, once again helped by stock performance of Amazon. If adjusted for inflation, that cumulative total would now be over $144 billion in 2018. That eclipses the record previously held by Microsoft founder Bill Gates, who is now in second place with a net worth of $93.3 billion. But he has given much of that away.