In this study, MnP single crystals were synthesized and comprehensively characterized to elucidate their structural quality, magnetic behavior, magnetocaloric response, and field-dependent critical phenomena along the easy $c$ axis. High-resolution x-ray diffraction confirmed the orthorhombic MnP-type crystal structure with excellent crystallinity. At the same time, magnetization measurements revealed a sharp ferromagnetic transition near room temperature. To further understand the underlying physics governing these behaviors, the critical exponents β, γ, and δ were systematically extracted in three distinct magnetic-field regimes, low, medium, and high, thus enabling a detailed assessment of universality and crossover effects in this anisotropic itinerant ferromagnet. In the low-field regime, we obtained a Curie temperature $T_{\mathrm{C}}=288.69\pm 10.01\mathrm{K}$, with critical exponents $\beta =0.355\pm 0.016, \gamma =1.208\pm 0.021$, and $\delta =4.407\pm 0.167$. For medium fields, the transition sharpened and shifted toward higher temperature, yielding $T_{\mathrm{C}}=294.52\pm 4.08\mathrm{K}, \beta =0.368\pm 0.022, \gamma =0.995\pm 0.010$, and $\delta =3.701\pm 0.031$. In the high-field regime, the system displayed a pronounced crossover from nearly second-order to more mean-field-like behavior, with $T_{\mathrm{C}}=300.26\pm 2.00\mathrm{K}, \beta =0.490\pm 0.049, \gamma =1.058\pm 0.035$, and $\delta =3.158\pm 0.227$. These systematic variations indicate strong field sensitivity of the magnetic interactions and highlight a continuous evolution of the critical behavior across the three regimes. The intrinsic thermodynamic $T_{\mathrm{C}}$ is approximately 296 K, while the field-dependent values extracted from modified Arrott plot/Kouvel-Fisher analyses represent effective crossover temperatures. This work provides a unified picture of the structural, magnetic, magnetocaloric, and critical properties of MnP single crystals. The field-dependent critical exponents demonstrate that MnP exhibits nonuniversal scaling governed by magnetic anisotropy and external-field strength, offering valuable insight into both fundamental studies of criticality and the optimization of MnP-based magnetocaloric materials near room temperature.

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• Ferromagnetism
• Magnetic phase transitions
• Magnetic susceptibility
• Magnetocaloric effect