Ahmed Hassan opened the score for Egypt from a penalty-shot in the 33rd minute and Hossam Hassan doubled the lead eight minutes later before DR Congo pulled one back with a Abdul-Zaher El-Saqqa own-goal.
Emad Meteb extended Egypt’s lead with the third goal two minutes from the hour-mark before Ahmed Hassan put the icing on the cake in the injury time.
Egypt will next play against Senegal, who qualified to the semis after defeating Guinea 3-2, earlier on Tuesday.
The 'Pharaohs' dominated the pitch throughout the match but squandered many chances to score.
Amr Zaki was awarded a penalty-shot, after a rough tackle by a Congolese defender, which Ahmed Hassan fired into the net to grab the lead for Egypt.
Egypt captain Hossam Hassan put the home side two up when he chested down Zaki's neat volley and slammed the ball into the roof of the net.
Egypt looked intent on ending the first-half in their favor, but a El-Saqqa blunder sent the ball straight into Al-Hadari’s net to award DR Congo their first goal deep into the first-half’s additional time.
Meteb went on to score Egypt’s third goal after Zaki drove the ball into the box before clashing with a Congolese defender, forcing the ball into the path of the Ahli striker, who eased it into the net.
Mbala Mbuta "Biscotte" almost pulled one back for DR Congo after rounding his way into the box and firing a throbbing shot that hit the bar.
Ahmed Hassan completed the rout in the dying seconds after curling a free-kick into the far left corner of the net, leaving the goalkeeper clueless.