Due to their attractive band gap properties and Van de Waals structure 2D binary chalcogenides materials have been widely investigated in the last decade, finding applications in several fields such as catalysis, spintronic, and optoelectronic. Ternary 2D chalcogenide materials are a subject of growing interest in material science due to their superior chemical tunability which endows tailored properties to the devices prepared thereof. In the family of AIIBIII2XVI4, ordered ZnIn2S4-like based photocatalytic systems have been studied meticulously. In contrast, reports on disordered phases appear to a minor extent. Herein, a photo-electrochemical (PEC) detector based on the pseudo-binary MnIn2Se4 system is presented. A combination of optical measurements and DFT calculations confirmed that the nature of the bandgap in MnIn2Se4 is indirect. Its performances outclass parent compounds, reaching responsivity values in the order of 8.41 mA W-1. The role of the non-centrosymmetric crystal structure is briefly discussed as a possible cause of the improved charge separation of the photogenerated charge carriers.