Bismuth selenide (Bi₂Se₃) is a widely recognized three-dimensional topological insulator with promising applications in the field of thermoelectric, optoelectronics, and spintronics. Here, we have synthesized Bi₂Se₃ nanosheets by solvothermal technique and studied their structural, morphological, and magnetic properties with varying solvothermal reaction times. The X-ray diffraction (XRD) studies showed a phase-pure trigonal Bi₂Se₃ with (015) plane-oriented growth. Fourier-transform infrared spectroscopy (FTIR) analysis confirmed the characteristic Bi–Se bonds and some residual organic species from precursors. The nanosheet-like morphology was demonstrated through scanning electron microscopy (SEM) analysis. Magnetic measurements exhibit dominant diamagnetic behavior, mixed with a subtle ferromagnetic response at 60 K and 300 K. The observed weak ferromagnetism may be attributed to intrinsic point defects or unintentional doping during synthesis.