Dan Jukes will take over the role as the MEP's press officer on 1 January. Jukes will retain his existing responsibilities for Nigel's digital output.
Heaver is moving on to what a press release from Jukes calls "an exciting new project", believed to be a start-up agency of some form. Heaver said he would provide more details in the new year.
Heaver, who previously chaired UKIP's youth arm Young Independence, said: "It has been an absolute honour and privilege to work for a man who has changed the face of politics in the UK and beyond. Without Nigel, Brexit would never have happened. Nigel is a true giant of global politics and I wish him all the best as he continues to battle for Britain."
Farage thanked Heaver for his work, and wished him "every success going forward".
In 2013, the then 16-year-old Jukes was reported by a local newspaper to have performed a rap at the party's conference, in which he addressed Labour leader Ed Miliband with the lines: "Why can’t your party win the south? Because no common sense comes out of your mouth."