Fiji 49 Namibia 25
Fiji wing Vereniki Goneva scored four tries as the South Sea Islanders opened their World Cup campaign in style at Rotorua International Stadium.
Goneva posted his hat-trick before the interval, and then added another touchdown after the break to help secure a comprehensive Pool D success.
Namibia had their moments, notably through the kicking of fly-half Theuns Kotze.
Kotze landed three dropped-goals in four minutes during the opening period, but once Fiji found their attacking rhythm, there was no stopping them.
Saracens star Jacques Burger, the Namibia captain, did his best to rally a fightback, and they managed second-half tries through lock Heinz Koll, after an audacious dummy, and full-back Chrysander Botha.
Kotze finished with 15 points, but Fiji are determined to at least match their World Cup achievement of four years ago when they reached the quarter-finals before bowing out against eventual winners South Africa, and they responded strongly.
Goneva was followed over the line by lock Leone Nakarawa, and there was a late try from Naipolioni Nalaga, with Castres fly-half Seremaia Bai slotting five conversions and three penalties for a 19-point haul.
With the Springboks, Wales and Samoa also in their group, it was paramount Fiji made a strong start and collected a winning bonus point against the group minnows.
All their anxious moments came early on as Kotze kicked relentlessly, becoming only the fourth player to drop three goals in a World Cup game after Jannie De Beer, Jonny Wilkinson and Juan Martin Hernandez.
It underpinned a solid start by Namibia in the sunshine, but Fiji quickly clicked, and it was 27-year-old Goneva who benefited by hauling Fiji into an unassailable 32-15 half-time lead.