To be fair, this won't be the first time Icahn has said words in support of Trump. Earlier this month, he told Fox News Trump had "hit a very important nerve".
"I think a lot of what [he] says has to be done in this country or we're going to have real problems," he said.
But he told Bloomberg that the 15-minute video amounts to him officially backing Trump.
"I would say it's an endorsement," he said.
"I'm behind Trump.... the basic thing is, you need somebody that can get things going in Congress, and I think he can do it. You need somebody that understands business, and I think he understands it."
It's been rumoured Icahn could be made Treasury secretary if Trump wins the 2016 Presidential election. However, the investor has previously denied this, saying "I have my day job".