John M. Cabello has served as a Republican member of the Illinois House of Representatives since his appointment in August 2012. He represents the 68th district, which includes all or parts of, Rockford, Machesney Park, Loves Park and Cherry Valley. Prior to his appointment, he was a member of the Winnebago County Board and the Harlem Township Board.
During the 2016 U.S. presidential election, Cabello was a co-chair of the Illinois Trump Victory Committee, supporting Republican candidate Donald Trump.
During the COVID-19 Pandemic, John Cabello wrote an editorial titled "Illinois must fight releasing prisoners during the COVID-19 pandemic" arguing that prisoners "...who are elderly and medically vulnerable, and those with pathways to release" should not be rehoused into empty hotel rooms for isolation purposes and called on the Governor to fight a civil rights lawsuit related to this all the way to the Supreme Court.