Large White x Landrace boars (n = 48) were used to determine the effect of dietary magnesium aspartate supplementation (MgAsp) on subsequent stress and meat quality indicators. Dietary MgAsp supplementation increased plasma magnesium levels compared with pigs fed the control diet. Pigs fed the MgAsp-supplemented diet had lower norepinephrine concentrations at slaughter than pigs fed the control diet. Pigs fed the MgAsp-supplemented and the control diet had similar glycogen concentrations in the longissimus thoracis (LT) and biceps femoris (BF) muscle, whereas pigs fed the MgAsp-supplemented diet had lower lactic acid in the LT and BF muscle compared to pigs fed the control diet. Negative handling of pigs before slaughter reduced muscle glycogen in the LT and the BF muscle and increased the lactic acid levels in the LT and BF muscle compared to when pigs were minimally handled at the abattoir. Comparison of meat quality traits indicates that MgAsp supplementation to pigs raised the muscle pH in the LT muscle at 40 min and 24 h after slaughter. Pigs that were fed the MgAsp-supplemented diet had lower percentage of drip loss, lower surface lightness L, and had no PSE carcasses compared to pigs fed the control diet. Also, pigs that were fed the control diet and negatively handled at the abattoir before slaughter had the highest percentage of drip loss and incidence of PSE compared to other treatment groups. The results indicate that dietary MgAsp supplementation to pigs can significantly improve ultimate meat quality and reduce the incidence of PSE meat.