In second place is Microsoft (NASDAQ: MSFT) co-founder, Bill Gates, who is worth $90 billion.
Most of his fortune is tied to Amazon shares which have risen from $846 a share last March to $1,523 per share last night.
Mr Bezos' fortune has leapt to $112bn from an estimated $39.2bn past year.
This year's rich list is the magazine's latest edition, entititled "The super-rich continue to get richer, widening the gap between them and everyone else".
It means Trump is ranked 766th in this year's rich list, down from 544th last year, when Forbes wiped $1bn off his wealth - again down to falling property prices.
(NYSE:BRK.A,BRK.B) investor has a net worth of $84 billion that puts in in third on this list.
The richest person in Europe and fourth on the list is the boss of luxury goods firm LVMH, Bernard Arnault, who has a fortune of $72bn.
You have to scroll all the way down to #16 to find the first woman to appear on the list.
The improvement in Mr Bezos' fortune is the biggest on record. His fortune is up from $75.6bn a year earlier.
Forbes adds while Trump's $3.1 billion fortune is "a far cry" from the $10 billion-plus he once claimed, it still makes him the richest president in US history.
The magazine went on to point out that Trump's golf properties have seen a revenue bump in three of the president's largest clubs, which happened to be in states that voted for him.
Donald Trump has dropped more than 200 places in the Forbes world ranking of billionaires as his fortune slumped to an estimated $3.1 billion (£2.2 billion).
Griffin, the founder of Citadel LLC, ranked 172nd worldwide with an estimated net worth of $9 billion in Forbes' 32nd annual World's Billionaires List.
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