A substantial improvement in the challenging photocatalytic arylation of white phosphorus (P4) with aryl chlorides and bromides is reported. Using the readily accessible deazaflavin-based photocatalyst o-Me-dFl, valuable triarylphosphines (PAr3) and tetraarylphosphonium salts ([PAr4]X, X = Br, Cl) are synthesized from P4 under near UV-LED (365 nm) irradiation in up to 87% combined yield with drastically reduced reaction times compared to previous protocols. 31P nuclear magnetic resonance spectroscopic monitoring studies and density functional theory calculations provide insights into the reaction pathway. The results represent an important step toward more atom-efficient and economical photocatalytic P4 functionalization reactions.