Fly-half Stephen Jones opened the scoring for Wales with a penalty kick, before centre Scott Williams darted down the left wing for an unconverted try.
Winger Aled Brew picked up Wales’s second, followed by number eight Toby Faletau, who broke through two Namibia defenders for the try – both converted by Jones.
The scored remained at 22-0 for the next 20 minutes until the break, but Namibia’s only real chances of getting points came from two penalty efforts by fly-half Theuns Kotze, but both attempts were missed.
Namibia applied the pressure coming out of the break, but Scott Williams got his second try for Wales after eight minutes and collected the bonus point in the process.
Prop Gethin Jenkins ran one in with two brushed-off tackles and a dummy to sweeten his first appearance after a lengthy injury lay-off, but Namibia responded soon after with a try from lock Heinz Koll, converted by Kotze.
Replacement George North went over for Wales’s sixth, followed minutes later by a converted try from Jonathan Davies to make it a half century for Wales.
19-year-old winger North went over for his second 68 minutes in, and Williams got his hat-trick shortly after, with both tries converted by replacement Rhys Priestland.
Lloyd Williams got Wales’s 10th, followed by tries from Lee Byrne and Alun Wyn Jones.
Wales play their final pool stage match against Fiji on Sunday, October 2.