It will be the first time Spain have reached the final, which will be held in Lagos on Saturday, since they lost the 1985 championship game to Brazil 1-0 in Moscow.
Spain, the only unbeaten team in the three-week tournament, controlled the game from the start, with the defenders Carlos Marchena, Francisco Jusue and Pablo Coira blunting nearly every Mali foray.
Pablo Gonzalez, Varela and Jose Javier Barkero wreaked havoc up front, starting when Barkero took the ball in midfield, weaved his way to the left edge of the area and crossed it to Varela, who drove it past the Mali goalkeeper, Boubacar Keita.
Gabri Garcia de La Torre, who missed several chances in the first half, set up the second goal in the 24th minute. He raced to the byline on the left and crossed to Varela, who converted easily from close-range. Varela then had a third goal disallowed for offside two minutes before half-time.
Unlike Spain, Mali never created a single chance in the opening 45 minutes and the forwards Mamadou Bagayoko and Mamadou Diarra showed none of the threat they exhibited in earlier games.
The second half started as the first, with Spain on the attack as Pablo sent the ball narrowly wide a minute after the restart. Mali finally scored in the 51st minute through Mahamadou Dissa before Pablo and Francisco Jusue reasserted Spain's dominance.
Abdoulaye Camara provided Mali with one last hope in the 78th minute, chesting down a ball 10 yards from goal, only to see it kicked away by the Spanish keeper Daniel Aranzubia before he could shoot.
Spain finished off the Africans four minutes into injury time, Xavi Hernandez's powerful shot from the right apex of the penalty box finding the net.
MALI: B Keita; D Coulibaly (M Dissa, 35), A Traore, A Coulibaly, S Baba Cisse, M Bagayoko, S Keita, A Coulibaly, A Camara, M Diarra, S Diakite.
SPAIN: D Aranzubia; P Coira, D Bermudo, F Jusue, P Orbaiz, C Marchena, G Garcia De La Torre, X Hernandez, P Gonzalez (F Yeste, 76), F Varela, J Javier Barkero (R Suarez, 81).
Referee: Lu Jun (China).Reuse content