We report a scalable, one-step fabrication of flexible graphene–gold nanocomposite electrodes via direct laser writing on polyimide substrates using an affordable continuous wave diode laser. Simultaneous laser-induced carbonization of polyimide to porous laser-induced graphene and reduction of gold(III) acetate to uniformly distributed gold nanoparticles yields a conductive and electroactive laser-induced graphene/Au composite. Comprehensive characterization by scanning electron microscopy, energy dispersive X-ray spectroscopy, Raman spectroscopy, and X-ray photoelectron spectroscopy confirms the formation of a defect-rich graphene framework decorated with Au nanoparticles, with optimal laser parameters providing a minimum sheet resistance of 87 ± 5 Ω. The developed LIG/Au electrodes exhibit excellent electrochemical performance for the simultaneous detection of dopamine and paracetamol, achieving detection limits of 16 nM and 36 nM, respectively. Dopamine detection spans two linear ranges (0.1–50 μM and 50–300 μM) with sensitivities of 1.09 and 0.09 μA μM−1 cm−2, while paracetamol shows a single linear range (0.1–200 μM) with a sensitivity of 0.35 μA μM−1 cm−2. The flexible sensor demonstrates high selectivity against common biosensing interferents, remarkable mechanical robustness under cyclic bending, and long-term stability with more than 90% signal retention over 30 days. The proposed direct laser writing technique represents a rapid, low-cost, and easily scalable approach for high-throughput fabrication of robust, flexible electrodes suitable for multi-analyte electrochemical analysis.