Lotus-flower-like heterostructures of Bi2S3/FeS with diverse morphologies and stoichiometries were successfully synthesized using a facile hydrothermal technique. The flower-like architecture and FeS content were controlled by adjusting the amount of l-cysteine during precursor synthesis. Electrochemical properties were explored through a combination of Raman and impedance spectroscopy, revealing the relationship between catalytic performance and the stoichiometry of Bi2S3/FeS. Due to the synergistic interaction of S anions with 3d electrons at the Bi2S3/FeS interface the heterostructures exhibited highly enriched overall water-splitting ability, achieving a remarkably low cathodic and anodic overpotential of 36 and 230 mV for a current density of 10 mA/cm2. Furthermore, the addition of methanol and urea in the electrolyte further enhanced the catalytic efficiency of Bi2S3/FeS, achieving a very high current density of 100 mA/cm2 at exceptionally low potentials of 1.5 V and 1.43 V for methanol and urea oxidation reaction. The excellent electrocatalytic properties of Bi2S3/FeS were attributed to the interactions and interfacial effects between Bi2S3 and FeS, leading to enhanced surface roughness, inhomogeneity, and the creation of additional electrochemically active sites. Notably, Bi2S3/FeS demonstrated long-term stability and excellent mass transportation capabilities, highlighting its potential for various practical applications. The remarkable element gradient in the heterostructures further contributes to their superior performance, making them highly promising candidates for diverse applications.