According to Forbes and Bloomberg, the Amazon CEO had a net worth of over US$89 billion (S$121 billion) as of the close of markets Wednesday, while Microsoft co-founder Bill Gates had a net worth of just over US$90 billion.
Even if Bezos didn't end the day as the richest man, he will likely take the crown from Gates more permanently in the coming days and weeks.
When he hits the mark, Bezos, who started selling books from his garage 22 years ago, becomes the first man to bump Gates from his perch in seven years and is only the sixth man to hold the "richest person" title in the past 30 years, according to Forbes.
Bezos' rise carries important symbolic weight - signaling Amazon's unbridled power and value, presenting a new face of outsized wealth to the world and heralding a new kind of billionaire who is sceptical of philanthropy and has massive reach in culture, technology and media.
Bezos will be a stark contrast to his fellow Seattle-area resident Gates, who has topped the list for much of the past quarter-century and devotes his time and money to philanthropy.
What's most astounding about Bezos' rise is his recent wealth surge. He has been a billionaire for nearly 20 years, first making the Forbes list in 1998 with a net worth of US$1.6 billion after Amazon's IPO.
He chugged along for the following decade, reaching US$4.4 billion in 2007, gradually rising to US$18.4 billion by 2012, ranking him 26th on the list.
But over the past two years, as Amazon's stock has soared, so has Bezos' fortune.
He owns 79.9 million shares, or just under 17 per cent of the company.
His net worth has grown by US$70 billion over the past five years, surging by US$45 billion in the last two years alone - possibly the largest wealth-creation surge in history.
Of course, Bezos avoids talking publicly about his wealth. Like most tech tycoons, he insists he's trying to change the world rather than get rich.
In his commencement speech at Princeton, Bezos said he had the idea of selling books on the internet while he was working at a New York hedge fund.
Torn between his high-paying job and a risky start-up, he chose the start-up.
"I took the less safe path to follow my passion and I'm proud of that choice," he said.
Bezos may not only be the richest man in the world today - he might become the richest man ever, at least measured in pure dollars.
At his peak Gates was worth US$90 billion, marking the largest single fortune ever.
With little sign that Amazon's momentum may be slowing, Bezos could well be the first 12-digit man, worth US$100 billion one day.
On Thursday, a leading analyst said that Amazon "could be the first trillion-dollar company" with its stock doubling to US$2,000.
Indeed, Bezos' rise to the top of the rich list shows just how large and fast today's biggest fortunes have become.
In the 1980s, Saudi businessman Adnan Khashoggi was considered the richest man in the world with a net worth of around US$4 billion. By 1995, when Gates first became the richest man, he was worth US$12.9 billion.
By 2005, Gates was still topping the list at US$50 billion.
In 1987, according to Forbes, there were 140 billionaires in the world with a combined net worth of US$295 billion.
Now, billionaires number 2,043 and have a combined US$7.7 trillion. In fact there were more new billionaires in the world in 2016 - 233 - than the entire population of billionaires in 1987.
Gates has been the richest man for 18 of the past 23 years.
The only interlopers were Carlos Slim of Mexico, who was the richest man between 2010 and 2012, and Warren Buffett, who was the richest in 2008.
Indeed, with the exception of Slim and the occasional overseas billionaire, Gates and Buffett have been a duopoly at the top of the rich list. Their close friendship and partnering in philanthropy made them a potent symbol of the philanthropic side of wealth.
Bezos will be a different figurehead. Unlike Gates, he is still actively running and building a business.
He is far more press-averse, rarely giving interviews or public addresses. He is hyper-competitive. And he is only moderately - some would say barely - philanthropic.
But like Gates and Buffett, Bezos is not given to many flashy displays of wealth. He has loads of real estate - he bought the most expensive home in Washington, D.C., and owns homes in Beverly Hills, California, and New York along with his spread in Medina, Washington - and is one of the nation's largest landowners, with over 300,000 acres.
He also owns The Washington Post and founded Blue Origin, the space-travel company.
Yet Bezos drove his 1996 Honda Accord long after he became a billionaire.
When asked how his life changed when he became a billionaire he said: "Personally, it hasn't changed at all. The big difference is that we now have US$50 million in the bank, which is huge."
With a net worth topping US$90 billion, Bezos' definition of "huge" may have changed.