Mr Icke is selling T-shirts on his website with a face that is half Trump’s and half Clinton’s, with the slogan “This choice is no choice”.
The former TV sports presenter is among a number of people who believe Trump has created an “outsider” but populist and right wing character to win over the Republican voters, and oust the other more traditional candidates as he has successfully done.
But, the conspiracy follows Trump, who is now behind Clinton in the polls, will never win the actual final race, leaving the door to the White House open for Hillary.
The conspiracy centres around Trump’s former close connections to the Clintons, his funding of their Clinton Foundation, and his membership of the Democratic party for several years during the 2000s.
It has even been suggested on record during the election TV debates that Bill Clinton phoned Trump just before he announced he was standing for the Republicans.
A number of videos have emerged online putting forward the theory and highlighting stances Trump took in the past which were more in line with Democratic policies, such as being pro-choice with abortion, supporting gay rights, providing state healthcare and wanting to bring in gun controls.
Mr Icke, who is currently in the US as part of a world tour promoting his theories, said in a YouTube video: “Election after election into infinity what we are seeing is increasingly obvious we have two candidates who are nothing more than masks on the same face.
“What is the point in voting for two people controlled by the same force?
“It is a one-party state with a so-called fee democracy, when another person comes along like Trump, I can see the way people think this guy is different.
“The guy claims to be a billionaire who made his fortune overwhelmingly in property and that requires an enormous amount of cash flow from the financial system.
“If Donald Trump wasn’t servicing or accepting of that system, they could have crushed him at any time.”
In an article on his website, Mr Icke wrote: “‘Is Donald J Trump running a false flag campaign to help Hillary?
“This idea was originally floated as a Republican Party conspiracy theory back in August, but failed to gain any traction by virtue of Donald Trump’s abrupt surge in national GOP polling.
“That’s changing now, as reality is starting to dawn on The Donald Show.”