Second half goals from Gbolahan Salami, ThankGod Ike, Gabriel Reuben and Chinedu Ezimorah secured what proved to be a comfortable win in the end.
Amokachi's team have been reeling under the weight of public censure since being eliminated from the African Nations Championships by Niger, and the WAFU tournament is being seen as make or break for the former Super Eagles striker.
His wards started understandably shaky as they tried to impose their authority in the opening stages. But penetration was hard to find against a sturdy Benin defence, and when they did get behind, atrocious shooting cost them.
If the first half was a case of missed opportunities, it looked like continuing in the second, at least for the opening quarter hour.
But things changed when Gbolahan Salami converted a penalty on the hour mark and Amokachi reorganised his team with two substitutions.
It was one of those subs, Ejike Uzoenyi, whose contribution proved decisive. He was involved in the buildup to the delivery that saw ThankGod Ike plant a header into the net for 2-0, and then set up the best goal of the afternoon.
Picking up the ball down the left channel, the forward jinxed his way down the far side, taking two defenders along with him before squaring a cut-back into the gaping hole they had left behind for Reuben to side-foot a fine finish.
Uzoenyi was involved again in the last goal, sending a cross field ball to Ahmed Musa on the opposite side.
The League top scorer broke with pace, then laid on a low ball across the face of goal for the simplest of tap ins by Amokachi's final substitute Chinedu Ezimorah, who had been on the pitch for just about a minute and was having only his second touch.
Line-up: 1. Akpan Bassey, 2. Terna Suswan, 3. Mutiu Adegoke, 14. Gabriel Reuben, 4. ThankGod Ike, 5. Promise Onuh, 10. Ahmed Musa, 13. Ikechukwu Ibenegbu (Chinedu Ezimora), 17. Eugene Salami (Ejike Uzoenyi), 15. Solomon Okpako, 16. Gbolahan Salami (Uche Nwofor)
Subs: 12. Austin Brown, 6. Chibuzor Okonkwo, 8. Chinedu Ezimorah, 11. Taiwo Hassan, 7. Ejike Uzoenyi, 9. Uche Nwofor, 18. Agbim