Introduction: Sinonasal organizing hematoma (OH) is a rare, nonneoplastic lesion that often presents with epistaxis, a reddish mass, and destruction of the involved sinonasal structures. Due to its rarity, the demographics, diagnostic modalities, treatment strategies, and outcomes have not yet been studied in a large, long‐term study. Materials and Methods: Retrospect cohort of 112 sinonasal OH patients treated between 1997 and 2020 in a tertiary, university hospital were evaluated. Demographics, systemic comorbidities, sinonasal surgery history, serum laboratory tests, radiological findings, and treatment results were collected. The present study aimed to assess the accuracy of preoperative computed tomography (CT), Gadolinum‐enhanced magnetic resonance (MR), and punch biopsies in detecting sinonasal OH as the most likely diagnosis. In addition, incidental differences by age and year of diagnosis were calculated using the Poisson log‐linear regression model. Results: The median age was 44, and 58% were male. Fewer than 20% of these cases had a chronic systemic comorbidity, bleeding tendency, or sinonasal surgery history. MR had the highest accuracy of (87%) to detect sinonasal OH as the most likely diagnosis, compared with contrast‐enhanced‐CT (53%), punch biopsy (49%), and non‐enhanced‐CT (16%) (all <0.05). Sinonasal OH incidence did not vary by age, but the yearly rate significantly increased by 1.05 times over 23 years (p < 0.05). Notably, 84% of 112 patients received surgical removal through the assistance of an endoscope, and none had substantial bleeding without preoperative embolization. Conclusion: Sinonasal OH was observed regardless of age, sex, systemic comorbidities, bleeding tendency, prior sinonasal surgery, or trauma. Preoperative MR gives the highest accuracy for detecting this disease. Sinonasal OH may be safely managed with endoscopic‐assisted surgery removal without embolization. Level of Evidence: 4 Laryngoscope, 134:1581–1590, 2024 [ABSTRACT FROM AUTHOR]