Ivory Coast - who now await the victors of Thursday's second semi-final between Ghana and hosts Equatorial Guinea - are perennial underachievers in the competition, but now have a shot at winning their first title since 1992 thanks to goals from Yaya Toure, Gervinho and Wilfried Kanon.
Toure's was a stunning strike, though it was quickly cancelled out when Dieumerci Mbokani converted from the spot following Eric Bailly's handball.
An increasingly open game played into the hands of an Ivory Coast side boasting numerous attacking threats, with Wilfried Bony and Gervinho linking for the latter to make it 2-1 at the break, and Kanon put icing on the cake in the second half.
The two sides met in qualifying, sharing three points apiece in two games that yielded 10 goals, and Ivory Coast goalkeeper Sylvain Gbohouo was called into action early on, parrying a firm close-range strike from Jeremy Bokila.
Serey Die shot wide at the other end after Toure's set-piece delivery was cleared to the edge of the box, before the Manchester City midfielder showed his countryman the way.
The African Footballer of the Year pounced on a loose ball on the edge of the box and hammered home an unstoppable drive in the 21st minute.
DR Congo were handed a route back into the match almost immediately, though, as Bailly clumsily handled in the box, with Mbokani coolly levelling from the spot for his third goal of the tournament.
Florent Ibenge's side spurned a chance to take the lead eight minutes before the break, when Mbokani's composure deserted him as he looked to steer Yannick Bolasie's low cross towards goal.
And they were punished when Gervinho, who had struck the crossbar just moments before, collected Bony's pass before curling his shot past Robert Kidiaba.
DR Congo - who came from 2-0 down in their 4-2 quarter-final win over Congo - needed a response after the break, and received a boost when Ivory Coast started the second half with 10 men as Serge Aurier inexplicably emerged late from the tunnel.
Aurier shot wide from Max Gradel's pass soon after returning to the pitch, though, while at the other end, Bolasie's strong run and shot underlined DR Congo's threat.
But DR Congo's dreams of a first final appearance since 1974 were finally dashed in the 68th minute as Kanon stabbed home from inside the six-yard box after Aurier's powerful header was brilliantly kept out by Kidiaba.
This time a two-goal deficit proved insurmountable for Ibenge's side, who will at least be able to reflect on their best performance at the competition since 1998 ahead of a third-place play-off against Thursday's losers.
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