This work covers a Mg–Zn–Ca–Pr alloy fabricated by a novel method of mechanical alloying and spark plasma sintering (SPS). Currently, magnesium alloys used as biomaterials are mostly commercial alloys without consideration of cytotoxicity from the perspective of biosafety. So far, the tribological and cytotoxic properties of Mg–Zn–Ca–Pr alloys have not been investigated. Hence, in the article, the tribological properties, considering wear rate, wear resistance, coefficient of friction, and the roughness of the sintered Mg–Zn–Ca–Pr alloy, are investigated. Cytotoxicity assays have also been carried out. The ball-on-a-disc method is used in the tribological test. Samples before sintering by the SPS method are milled at varying times of 13, 20, and 70 h. Results show that increasing the milling time affects tribology and cytotoxic tests. The longer the milling time, the lower the cell survival rate. The conducted tests reveal cell survival of 90, 82, and 61% for 13, 20, and 70 h, respectively. A reduction of cell viability by over 30% is considered a cytotoxic effect, which was observed only in the 70 h milling-time samples.