Replacement winger George North added two tries, with Aled Brew, Toby Faletau, Gethin Jenkins, Jonathan Davies and Lloyd Williams, Lee Byrne and Alun Wyn Jones also crossing for Wales as they notched up their highest score at the World Cup.
Wales flyhalf Stephen Jones, who became the most-capped player for his country with his 101st appearance, slotted 15 points with the boot with six conversions and a penalty before being replaced by Rhys Priestland.
Namibia lock Heinz Koll sprinted 45 metres for his second world Cup try, which flyhalf Theuns Kotze converted to give the underdogs something to cheer about at Stadium Taranaki.