With dominant play on the pitch, Doris Boaduwaa netted twice with Portia Boakye sealing the victory in style with another goal, while an own goal by a Namibian defender gave the visitors a consolation score.
Despite a defensive mistake allowing Namibia to grab an away goal, Ghana holds a significant advantage heading into the second leg, scheduled for December 5 at the Lucas Moripe Stadium in Namibia.
Coach Nora Hauptle will be looking to maintain her impressive unbeaten record (10 consecutive wins) as coach of the Black Queens, and aims to qualify for the Women's Africa Cup of Nations in Morocco after missing the previous edition.