Utaka got a rare chance in Nigeria's starting line-up because of injuries to Obafemi Martins and Peter Odemwingie, and he wasted little time in taking advantage.
The younger brother of Montpellier's John Utaka opened the scoring after a minute following good work by Victor Anichebe.
He rounded Ethiopia's keeper to add a second in the 55th minute as Nigeria moved to within a point of Group B leaders Guinea at the halfway stage of the 2012 qualifiers.
Utaka then made way for injury-plagued Uche, who missed last year's World Cup because of a knee injury.
Uche took just seven minutes to mark his return with a goal from close range.
Odemwingie, who had been ruled out on Friday, came on as a second-half substitute and set up Uche's first goal, but a hamstring injury kept Martins from playing.
Uche made it 4-0 with a long-range effort in the final minute.
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