McIvor was selected to stand for the Conservatives in Hemel Hempstead in the general election. But hours from the deadline for nominations to be submitted he was dropped and suspended by the party pending an investigation.
It is understood his move away from the Conservative party is related to this.
A Conservative spokesperson said: “Mr McIvor was suspended by the party and removed from the candidates list in June.
“After a disciplinary hearing, he was expelled from the Conservative Party on 9 October.”
McIvor says he will “continue to serve my residents” as a Reform UK councillor on both Essex County Council and Epping Forest District Council.
Elections for Essex County Council are due to be held in May 2025.
Earlier this year, McIvor posted on X, external: “For every person that joins Reform UK , they become another campaigner for a Labour government, which would achieve the polar opposite to what they want to see changed.”
A spokesperson for Reform UK said: “We believe James McIvor has been the victim of vicious Tory infighting.
“We look forward to announcing many more councillors joining us in Essex from the Tory sinking ship.”
Essex Conservatives have been approached for comment.