The crystalline structure, magnetism, and magnetocaloric effect of a GdCrO_3 single crystal grown with the laser-diode-heated floating-zone technique have been studied. The GdCrO_3 single crystal crystallizes into an orthorhombic structure with the space group Pmnb at room temperature. Upon cooling, under a magnetic field of 0.1 T, it undergoes a magnetic phase transition at T_N-Cr = 169.28(2) K with Cr^3+ ions forming a canted antiferromagnetic (AFM) structure, accompanied by a weak

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... ism. Subsequently, a spin reorientation takes place at T_SR = 5.18(2) K due to Gd^3+-Cr^3+ magnetic couplings. Finally, the long-range AFM order of Gd^3+ ions establishes at T_N-Gd = 2.10(2) K. Taking into account the temperature-(in)dependent components of Cr^3+ moments, we obtained an ideal model in describing the paramagnetic behavior of Gd^3+ ions within 30–140 K. We observed a magnetic reversal (positive → negative → positive) at 50 Oe with a minimum centering around 162 K. In the studied temperature range of 1.8–300 K, there exists a strong competition between magnetic susceptibilities of Gd^3+ and Cr^3+ ions, leading to puzzling magnetic phenomena. We have built the magnetic-field-dependent phase diagrams of T_N-Gd, T_SR, and T_N-Cr, shedding light on the nature of the intriguing magnetism. Moreover, we calculated the magnetic entropy change and obtained a maximum value at 6 K and Δμ_0H = 14 T, i.e., –ΔS_M≈ 57.5 J/kg.K. Among all RECrO_3 (RE = 4f^n rare earths, n = 7–14) compounds, the single-crystal GdCrO_3 compound exhibits the highest magnetic entropy change, as well as an enhanced adiabatic temperature, casting a prominent magnetocaloric effect for potential application in magnetic refrigeration.