Authorities said a preliminary investigation determined there were no signs of foul play, the Spanish newspaper El Pais reported.
The 75-year-old eccentric tech entrepreneur was arrested in October and was awaiting extradition in the Barcelona jail when he was found dead by hanging, police sources told El Pais.
The newspaper reported McAfee was pulled from his cell in Barcelona and police are investigating the circumstances around his death.
"Everything points to suicide," the newspaper reported, citing justice department officials in the country. A second Spanish newspaper, El Mundo, also reported McAfee had died by an apparent suicide in the jail.