Single-process additive manufacturing provides fully functional 3D-printed structures in a single 3D printer without the need for additional manufacturing processes. The 3D-printed parts can be scaled, individualised, embedded, and combined into multi-functional structures without modifications to the fabrication technology. This manuscript reports the first demonstration of monolithically 3D-printed stacked dielectric actuators (SDEAs) in a single fabrication process utilising a commercially accessible extrusion 3D printer and thermoplastic filaments. Neither single-layer nor stacked dielectric actuators have been 3D printed with thermoplastic filament extrusion in a single process until now. To achieve single-process fabrication, this research successfully addresses the main challenges: single-process fabrication of the dielectric layer and electrodes, repeatability and reliability of the 3D-printed thin dielectric layer, and layer stacking. Four actuators with different active areas and a number of stacked active layers were 3D printed. The functionality of the 3D-printed actuators was demonstrated with dynamic electromechanical characterization in a free-displacement and blocked-force configuration in a broad frequency range (up to 5 kHz). The actuators show promise for applications that require high-frequency resonators or high controllability in the sub-resonance region.