TP53 mutations in patients with AML and MDS frequently portend a poor prognosis, related to both p53 allele status and blast count. In 2022, the ICC and WHO released updated guidelines for classifying p53-mutated AML/MDS. The characteristics of p53 mutations, their associated co-mutations, and their effects on overall survival (OS) are not known in the context of these new guidelines. A retrospective chart review was undertaken for all patients with AML or MDS and at least one TP53 mutation detected on next generation sequencing (NGS) at Yale New Haven Hospital from 2015 to 2023. All patients (N = 210) met criteria for one of the 5 diagnostic classes based on WHO and ICC guidelines. Kaplan-Meier curves with associated log-rank testing and Cox proportional hazards model quantified the effects of clinical and molecular data on survival. Multi-hit pathogenic mutations were related to poorer OS in MDS but not AML using either the WHO (p = .02) or the ICC (p = .01) diagnostic criteria. The most significant predictors of OS in the sample overall were platelet count < 50K (HR: 2.01, 95% CI [1.47, 2.75], p < .001) and TP53 VAF ≤ 40% (HR: 0.68, 95% CI[0.50, 0.91], p = .01). Blast count ranges, complex karyotype, and p53 mutation type or location, showed no association with OS. In our cohort defined by the 2022 ICC and WHO criteria, VAF and thrombocytopenia, rather than blast count or p53 mutation features, significantly predicted OS. These results speak to each criteria's ability to identify cases of similarly aggressive disease biology and prognosis.