This report demonstrates the fabrication of all MoS₂ based 2D/0D unipolar heterojunctions using a simple one pot hydrothermal process and their utilization in a flexible broadband photodetector covering the spectral range from the ultraviolet to the near infrared region. The discontinuous deposition of 0D MoS₂, which has absorbance in the UV region, on 2D MoS₂, having absorbance in the visible and near-infrared (NIR) regions, enables broadband detection. Further, contact engineering was performed wherein both the metal contacts were fabricated on 2D MoS₂, thereby enabling the effective capture of photogenerated carriers. Also, a unipolar junction formed due to the Fermi level difference between 2D and 0D MoS₂ produces a localized electric field that helps in the efficacious separation of photogenerated electron–hole pairs. The responsivity values of the fabricated photodetector were calculated to be 7.56 mA W⁻¹, 12.8 mA W⁻¹, and 3.95 mA W⁻¹ in the UV, visible and NIR regions, respectively, indicating that the fabricated device is more sensitive towards the visible region. A detailed understanding of the photodetection mechanism of this unique heterostructure is presented using bandgap theory and trap states. The successful demonstration of such a cost-effective, scalable 2D/0D based broadband photodetector should lead to potential applications in optoelectronics, security, and wearable electronics.