Human herpesvirus type 6 (HHV-6) is a DNA virus considered a member of the Herpesviridae family. HHV-6 is acquired early in life, when it may cause roseola infantum and nonspecific febrile illnesses which is usually a self-limiting disease before the age of two. Primary HHV-6 encephalitis and acute necrotizing encephalopathy (ANE) are rare diseases to occur in immunocompetent children. We describe an unusual case of HHV-6 encephalitis with mixed features of acute necrotizing encephalopathy and acute disseminated encephalomyelitis and contextualize it with a review of the literature on HHV-6 encephalitis in immunocompetent children. Although the incidence of primary HHV-6 encephalitis is rare in immunocompetent children, HHV-6 encephalitis associated with acute necrotizing encephalopathy is a devastating disease, highly fatal and neurologically damaging disease. Therefore, early testing and diagnosis are crucial as well as effective management of encephalitis with antiviral therapy is highly recommended.