Microsupercapacitors (MSCs) are attractive for use as energy devices to power wearables, IoT, and other small microsystems. Additive fabrication of these devices will facilitate easy integration into a range of ubiquitous microsystem platforms. In this work, MSCs with lateral sizes < 0.5 cm(2) (full package: 7 mm x 7 mm and charge storage active area: 4 mm x 3.5 mm) and total height of similar to 2 mm with remarkable electrochemical performance are fully 3D printed via a combination of FDM printing and 3D extrusion-based printing. By fine-tuning the chemistries of the components of the MSCs, a combination of high energy density of 16.1 μWh.cm(-2), power density of similar to 3028 mW.cm(-2), areal capacitance of similar to 323 mF.cm(-2), and similar to 91.3% capacitance retention after 21000 cycles are realized. These performance levels are achieved using novel inks for the electrodes, electrolytes, and current collectors in addition to provision of proper packaging and encapsulation of the devices. The demonstrated performance of these encapsulated millimeter-scale fully additively fabricated MSCs with thick electrodes (i.e., similar to 300 mu m) thus makes them attractive for use as integrated energy sources for powering microsystems, wearables, and IoT.