Patients with TP53 mutations in acute myeloid leukemia (AML) and blast phase myeloproliferative neoplasms (MPN-BP) experience similar poor clinical outcomes. A retrospective analysis of 39 patients with TP53 mutations (23 with AML and 16 with MPN-BP) revealed comparable mutation patterns associated with prognostic significance. A total of 47 distinct TP53 mutations were identified, including seven patients with multiple mutations. Based on clinical outcomes, we propose a two-tiered risk stratification for TP53-mutated AML and MPN-BP. The high-risk group mutations, such as splice site variants in Intron 4 (especially c.376), missense mutations in Exon 5 (notably p.R175H), and mutations in the oligomerization domain (OD), were associated with, particularly, worse overall survival (OS < 3 months). Conversely, single missense mutations in Exons 6 and 7 (notably p.Y220C, p.R248N, p.R248Q, and p.R248W), and mutations in the transactivation domain (TAD), constituted a low-risk group and were associated with relatively better prognosis (median OS: 10.15 months for the low-risk group vs. 1.3 months for the high-risk group, p < 0.0001). These findings support the hypothesis that distinct TP53 mutations can lead to varying cellular effects, therapeutic responses, and clinical outcomes. Consequently, acute myeloid neoplasms (AML and MPN-BP) harboring certain TP53 mutations may exhibit increased aggressiveness compared to other TP53 mutants, underscoring the need for prioritized clinical research and therapeutic targeting.