Background: Urothelial carcinoma of the bladder (UCB) demonstrates considerable heterogeneity, with markedly varying outcomes between non–muscle-invasive bladder cancer (NMIBC) and muscle-invasive bladder cancer (MIBC). The pan-immune-inflammation value (PIV), derived from routine hematological parameters, has emerged as a novel biomarker reflecting systemic inflammation and immune dysregulation. This pilot, exploratory analysis evaluated the prognostic relevance of the PIV in UCB and contextualized PIV against other inflammation-based indices. Methods: We retrospectively analyzed 119 patients with histologically confirmed UCB who were treated between 2019 and 2024. PIV was calculated as (neutrophils × platelets × monocytes) ÷ lymphocytes. Additional indices included the NLR, SII, SIRI, and PLR. Progression-free survival (PFS) and overall survival (OS) were estimated using Kaplan–Meier analysis, and prognostic factors were assessed using Cox regression. Results: Among 119 patients (median age, 72 years; 88% male), 68 were diagnosed with NMIBC and 51 with MIBC. Elevated PIV levels were significantly associated with NMIBC progression to MIBC (p = 0.028) and strongly correlated with NLR, SII, SIRI, and PLR. Patients with high PIV exhibited shorter OS (24 vs. 45 months) and PFS (20 vs. 35 months) than those with low patients (p < 0.001). Although the prognostic value was evident in the univariate analyses, PIV did not retain significance in multivariate models. Conclusion: Elevated PIV levels predict adverse survival outcomes and progression in UCB, underscoring its potential as a cost-effective and accessible biomarker for risk stratification. Prospective validation in larger cohorts is warranted to confirm its role in personalized patient management.