The Congolese became the second team to reach the last eight of the competition, joining hosts Rwanda, while Angola were eliminated after a second straight defeat.
Midfielder Nelson Munganga put Florent Ibenge's side ahead in the eighth minute when he scored from a rebound and hard-working Meschak Alia added the second ten minutes later.
Jonathan Bolingi added his name to the scoresheet with the third in the 38th minute for a 3-0 half-time lead.
Angola grabbed a lifeline in the 75th minute when Gelson Dala, following a solo run, split apart the DR Congo defence before finishing off with his left foot.
But DR Congo put the result beyond doubt with an 82nd-minute header from Merveille Bope, with Yano's effort a minute later not enough for Angola, who were knocked out of the 16-team competition.
Ethiopia then held Cameroon in the second match to stay alive in the competition.
The Walia Antelopes were desperate for a victory following their opening round defeat to DR Congo and threw everything at their opponents from the start.
They had two chances inside the opening 20 minutes when Gatoch Panom tested the Cameroon goalkeeper from distance, only for his shot to be deflected away.
Haile Mulualem also squandered an excellent chance when, with only the goalkeeper to beat, he shot agonisingly over the crossbar.
The final round of the group matches will be played on Monday when DR Congo take on Cameroon and Ethiopia meet Angola in Kigali.