The Pharaohs broke the deadlock 10 minutes before the break through Abdelmoneim’s close range header from Abdalla Mohamed’s outswing corner.
The record AFCON winners came into the match with the sole objective of qualifying to the knockout stages.
The Pharaohs were led by talisman and captain Mohamed Salah to take on Sudan who also needed a win to have any chance of progressing.
Egypt started brightly at the Stade Ahmadou Ahidjo in Yaoundé with Arsenal midfielder Mohamed Elneny firing over the goal inside the first minute.
Mohammed Hussein came close for Sudan with a low drive early on after Hegazy lost possession outside the Pharaohs box.
Mostafa Mohamed forced a save from Sudan goalkeeper Mohamed Mustafa Mohamed on the half hour mark.
The diminutive forward connected with Abdalla Mohamed’s inviting cross but the keeper was on hand to turn his header away for a corner.
Abdelmoneim was Egypt’s unlikely hero with a brilliant goal to beat Mustafa Mohamed and put Carlos Queiroz and his charges on the driving seat.
Sudan came into the second half looking for the equaliser and Egypt had El Shenawy to thank for keeping the level in their favourite. The Al Ahly keeper was quick to push away an inviting cross from the left for a corner as Sudan continued to push forward on the counter.
Mohamed Salah saw his right footed effort saved on the hour mark from close range, the Liverpool man beat two defenders before firing straight at the keeper who had a hand to it.
El Shenawy was again called to action 10 minutes from time with a brilliant double save to keep his second cleansheet of the tournament.
The victory seals the Pharaohs place in the round of 16 with 6 points, three behind first place Nigeria and five ahead of Guinea-Bissau and Sudan.
Source: CAF