Radio frequency/electromagnetic interference (RF/EMI) shielding within redistribution layers of a fan-out wafer level package is provided. By using RDL metal layers to provide the shielding, additional process steps are avoided (e.g., incorporating a shielding lid or applying conformal paint on the package back side). Embodiments use metal filled trench vias in the RDL dielectric layers to provide metal “walls” around the RF sensitive signal lines through the dielectric layer regions of the RDL. These walls are coupled to ground, which isolates the signal lines from interference or noise generated outside the walls.