Fellow New York businessman Icahn, who began his career as a stockbroker on Wall Street, has thrown his support behind the Republican candidate, saying Trump would reduce regulations on US companies.
Icahn said: "If you look ahead three years, this economy will be a lot better if Trump gets elected.
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There's a lot of problems I think what she wants to bring in — more government and bigger government
The Wall Street mogul said he fears that should Clinton win the race to the White House, she will hike taxes and increase regulations on businesses.
"There's a lot of problems I think what she wants to bring in — more government and bigger government."
He added: "Trump, on the other hand, will say, hey I'm going to change the regulatory agencies."
Trump has hinted that Icahn would make a great US Treasury Secretary – however whether the 80-year-old hedge fund manager would take up such a role remains unclear.
Icahn has been outspoken in his criticism of US regulators, saying there has been too much red-tape in the American system.
Mr Icahn said fear of "irrational" government regulations is the reason for a lack of investment by chief executives – and that Trump would reduce such regulations.
The founder of Icahn Enterprises also claimed those on Wall Street who were supporting Clinton were "wrong" and Trump would increase productivity in the US economy.
Icahn said: "They're wrong, because you need to do something about productivity in this country.
Trump Berates Clinton’s ‘Vicious Demonisation’ of His Supporters
"You don't have jobs and you don't have people working, sooner or later this blows up, and it blows up in so many different fashions."
While there has been more than 12million jobs created since the 2008 financial crash, wage growth and productivity has been relatively flat.