The Catalans, who pipped Mallorca 2-0 at Camp Nou last month in the first leg of the semi-final, won 3-1 on aggregate to secure a berth in the final.
Gonzalo Castro scored the opener for Mallorca late in the first half, and Barcelona scoring sensation Lionel Messi netted the equalizer nine minutes from time.
Barcelona suffered a blow when Jose Martin Caceres was sent off early in the second period as they were still a goal down.
Jose Luis Marti wasted a spot-kick for Mallorca, who were also reduced to ten men when Josemi received his marching orders.
Elsewhere, Athletic Bilbao reached the Copa del Rey final after beating Sevilla 3-0 in the second leg, 4-2 on aggregate.
Javier Martinez hit an early opener on four minutes, before Fernando Llorente doubled the lead for the home side and Gaizka Toquero put the icing on the cake three minutes after.
Not only did Bilbao secure a final berth, but they also avenged their last week's 2-1 loss to Sevilla in the Premiera Liga.