Introduction: Chromosomal abnormalities (CAs) have been identified as important factors in determining the biological features and prognostic value of multiple myeloma (MM). MYC gene-related abnormalities (MYC GAs) are one of the CAs, but their unfavorable impact has not been fully investigated in daily clinical practice. Methods: This study retrospectively analyzed the prognostic impact of MYC GAs on 81 patients through fluorescence in situ hybridization analysis in our institute. Results: MYC GAs were associated with poor overall survival (hazard ratio [HR], 3.08; 95% confidence interval [CI]: 1.23–7.73; p = 0.017), progression-free survival (PFS) (HR, 2.96; 95% CI: 1.58–5.53; p < 0.001), and time to next treatment (TNT) (HR, 2.11; 95% CI: 1.13–3.93; p = 0.018) in the median follow-up of 34.7 months. Furthermore, MYC GAs with an additional chromosome 8 (MYC-Ch8(+)) were associated with shorter PFS (HR, 3.15; 95% CI: 1.38–7.2; p = 0.0064), whereas MYC GAs without an additional chromosome 8 (MYC-Ch8(−)) were associated with shorter PFS (HR, 3.62; 95% CI: 1.51–8.68; p = 0.004) and shorter TNT (HR, 3.72; 95% CI: 1.41–9.81; p = 0.0078). Conclusion: These findings could help identify high-risk patients with MM. Further prospective studies are needed to confirm the significance of MYC GAs for the MM prognostic effect.