The home Eagles had to rely on a late goal by Anthony Okpotu in the 91st minute to drag the game into extra-time after Vladimir Va shot Angola into the lead on 55 minutes.
And in the 19th minute of second half extra-time, Okechukwu Gabriel scored the winner to send Nigeria into the semi-final.
Reacting to the win, Omeruo, who is on loan at Turkish top flight club Kasimpasa from Chelsea, hailed the coach Salisu Yusuf-led side for reaching the last four.
“Congrats my people.. through to the semi-finals.. big ups Nigeria Super Eagles,” Omeruo wrote on his Instagram page.
The home Eagles will now face Sudan in the semi-final on Wednesday, January 31, in Marrakech.
The second semi-final is between hosts Morocco and fellow North Africans Libya in Casablanca also on Wednesday.