The Eagles were made to work for a hard-fought 1-1 draw, after Jadan Raymond's first-half strike was cancelled out by Pablo Gonzalez's clinical finish midway through the second period.
But when Jose Luis Perez's penalty was saved by Owen Goodman, up stepped Palace's Trialist to win the game - five successful spot kicks from five putting the Eagles into the Final.
A full match report and highlights will follow shortly.
Crystal Palace: Goodman (GK), Trialist, Rodney, Balmer, Grehan, Adaramola (Watson, 105), Ozoh (Vigor, 110), Raymond, Mooney (Umeh, 72), Akinwale (Reid, 105), Omilabu (Nascimento, 90+3).
Subs: Izquierdo (GK), Sheridan.
Valencia: Perez (GK), Alemán, Iranzo, Muñoz, Agulló (González, 60), Soler (Navarro, 90), Gómez, Tejón (García, 105), Santana (Perez, 60), Rodrigues, Inoussa (Maia, 77).
Subs: Bernad (GK), Tárega.