Mthembu, whose contract with Platinum Stars expires at the end of the month, has agreed terms with Amakhosi.
"It's a done deal, it's a three-year contract," says a source.
Amakhosi football manager Bobby Motaung remained cagey about the imminent arrival of 'Shaka Zulu' at Naturena.
"We will release an official statement very soon," he says.
"We are waiting for the coach to arrive back before we announce who is coming and who is going."