The chief strategist at Hilltop Securities spoke as a new report said President Donald Trump could nominate his National Economic Council director to lead the Fed.
Citing four sources, Politico said Cohn is now the leading candidate to replace Yellen once her term ends in February. CNBC and other media outlets have also been buzzing for months about the possibility of a Cohn appointment.
Cohn, as the world's most important central banker, is needed because "we need a more pragmatic Fed," Grant said on "Squawk Box."
Before joining the Trump administration, Cohn was the No. 2 executive at investment bank Goldman Sachs. A Cohn appointment would break with a tradition of having an economist as Fed chairman.
For its part, the White House told CNBC that Cohn is focused on his responsibilities at the NEC, pointing to recent comments in which Cohn told MSNBC on June 29: "I love my job. Think of the opportunity I have. I have the opportunity to do something that hasn't been done in 30 years, which is reform the U.S. tax code. I have the opportunity to be involved in redoing the United States infrastructure, something that desperately needs to be done. I don't know how many people can sit here and tell you that they have that opportunity."
Meanwhile, Grant said current Fed Chair Yellen has hurt the economy with interest rate hikes, and anytime he hears the central bank talk about normalcy he winces.
"We are not in a normal world," Grant said. "We have the central banks in all over the world — Japan, ECB, even our own Fed — with the $4.5 trillion balance sheet. There is no normalcy. This is not normal, and I don't know why the Fed is talking about it."
The central bank reiterated its federal funds rate forecast in June, saying it still expects its benchmark rate to reach 1.4 percent by the end of 2017.
In the interview, Grant also spoke about Donald Trump Jr.'s email exchange with a Russian lawyer allegedly linked to the Kremlin. He said the chatter was "fluff" and the markets will likely focus on fundamentals and earnings.
It's getting increasingly difficult to know "what's real about anything," he said.
Grant said on the morning of Election Day that investors would be smart to buy stocks in the event of a surprise Trump victory.
That advice sure paid off. Since the election, the Dow Jones industrial average has surged more than 16 percent, the S&P 500 has gained 13 percent and the Nasdaq composite has risen 19 percent as of Tuesday's close.
Grant has since said he thinks the Trump rally is over, and investors should employ a new strategy to make money. Still, he said the Trump agenda is not dead and will likely be extended out.