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Using X-ray diffraction (XRD) and a vibrating sample magnetometer (VSM), the effects of Sm substitution, wheel speed, and annealing temperature on the phase formation and magnetic properties of (Y_1−xSm_x)Co₅ (x = 0.2, 0.3, 0.4, 0.5) melt-spun ribbons were investigated. The results indicate the following: (1) With the increase in Sm substitution, it was found that (Y_1−xSm_x)Co₅ ribbons are entirely composed of the (Y-Sm)Co₅ phase with a CaCu₅-type structure. Additionally, the coercivity gradually increases, while the remanence and saturation magnetization gradually decrease. (2) As the wheel speed increases, the (Y_1−xSm_x)Co₅ ribbons exhibit an increasing proportion of (Y-Sm)Co₅ phase until reaching a speed of 40 m/s, where they are entirely composed of the (Y-Sm)Co₅ phase. Magnetic measurements show that the coercivity (H_cj) and remanence (B_r) of (Y_0.5Sm_0.5)Co₅ ribbons increase gradually with increasing wheel speed, while saturation magnetization decreases. The variation in magnetic properties is mainly attributed to the formation of nucleation centers for reversed magnetic domain (2:7 and 2:17 phases); (3) (Y_0.5Sm_0.5)Co₅ ribbons are composed of the (Y-Sm)Co₅ phase and a small amount of the Sm₂Co₇ phase after annealing at 550 °C, 600 °C, and 650 °C. Temperature elevation promotes crystallization of the amorphous phase, resulting in a gradual decrease in coercivity, while the remanence and saturation magnetization exhibit an overall increasing trend. Through continuous optimization of the process, favorable magnetic properties were achieved under the conditions of a 0.5 Sm substitution level, a wheel speed of 40 m/s, and an annealing temperature of 550 °C, with a coercivity of 7.98 kOe, remanence of 444 kA/m, and saturation magnetization of 508 kA/m.