Some prognostic markers have been shown to determine the course and survival of Urothelial Cancer. A cross-sectional retrospective study, specifically looking at the role that various indices related to platelets—namely Mean Platelet Volume (MPV), platelet count and MPV/Platelet ratio—play in the diagnosis and prognosis of urinary bladder cancer, was conducted at the Department of Pathology, Geetanjali Medical College and Hospital, Udaipur, Rajasthan (India) between January 2016 and August 2021 and included 76 patients who underwent multicore TURBT biopsy. Complete Blood Count (CBC) was used to determine platelet count, MPV and MPV/Platelet ratio. Platelet count was found to be more elevated in patients with high grade urothelial carcinoma and muscle invasive urothelial carcinoma as compared to patients with low grade urothelial carcinoma and non-muscle invasive urothelial carcinoma (p < 0.05). The median MPV and MPV/PLT ratio was found to be significantly lower in patients with high grade urothelial carcinoma and muscle invasive urothelial carcinoma as compared to patients with low grade urothelial carcinoma and non-muscle invasive urothelial carcinoma (p < 0.05). Thus, platelet indices can be useful supportive prognostic and diagnostic indicators in the determination of the clinical outcome of urothelial carcinoma.