Fiber-shaped energy storage devices have great potential for use as an intelligent power source for futuristic wearable technology. To produce high-performance fiber-shaped energy storage devices, a thin fiber material with a high energy density, shape adaptability, and longevity is critical. Herein, 3D fiber-shaped supercapacitors (SCs) comprising MXene-PEDOT:PSS active electrodes made using the 3D-direct-ink-writing (DIW) technique are demonstrated. Embedding a silver (Ag) current collector in the active electrode facilitated faster charge transport in the fiber-shaped 3D-SCs, enabling them to create a unique 3D-electrode structure that solves the thickness and length problem of electrode-dependent capacitance in fiber-shaped devices. At one-meter long, the fully-printed fiber-shaped 3D-SC exhibits a low charge transfer resistance that leads to the high areal capacitance of 1.062 F cm−2 and gravimetric capacitance of 185.9 F g−1, with a high areal energy density of 94.41 µWh cm−2 at a power density of 1,142 µW cm−2. The fiber-shaped 3D-SCs also exhibit excellent electrochemical and mechanical stability at different temperatures in air and water. With their unique electrode structure and uninterrupted power supply, these R2R 3D-DIW printed fiber-shaped SCs can boost the development of innovative textile technology.