The synthesis of poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) a benchmark conducting polymer frequently researched for energy storage, conventionally relies on corrosive and toxic reagents leading to significant hazardous waste, conflicting with the principles of green and sustainable chemistry. This report introduces a fully photochemical, metal-free, and sustainable method that employs a single organic photoinitiator, phenacyl bromide (PAB), to achieve the in-situ polymerization of 3,4-ethylenedioxythiophene (EDOT) and sodium 4-styrenesulfonate (NaSS) monomers. The reaction occurs at room temperature in a benign ethanol/water solvent system. A major environmental advantage is the elimination of hazardous metal waste, replaced instead by acetophenone, a non-toxic byproduct readily removed via simple precipitation. Structural analysis confirmed the formation of the doped polymer with a PEDOT:PSS molar ratio of approximately 1:3, consistent with both Nuclear Magnetic Resonance (NMR) and X-ray photoelectron spectroscopy (XPS) bulk and surface measurements, respectively. As a proof-of-concept for its application in energy storage, the resulting PEDOT:PSS/Activated Carbon composite was fabricated into a symmetric supercapacitor device demonstrating an exceptional operational durability, retaining 97% of its initial capacitance after 2000 charge–discharge cycles. Moreover, this light-driven synthesis can enable spatiotemporal control, opening new pathways for sustainable advanced manufacturing, such as 3D printing of PEDOT:PSS, in line with SDG 9 goals.