Background: In 2019, after the first case was discovered in Wuhan, China, the COVID-19 virus began to spread rapidly across the world, leading the WHO to declare the disease a public health emergency. Objectives: Thromboembolism refers to the formation of a clot in a vein, which then travels through the vascular system, potentially blocking blood flow in another location. Methods: This retrospective cohort study aimed to investigate the risk factors for pulmonary embolism in COVID-19 patients hospitalized at Firoozabadi Hospital from May to the end of December 2020. After extracting the required information, the data was entered into SPSS version 26 software for analysis. Results: In total, data from 283 COVID-19 patients admitted to Firouzabadi Hospital in Tehran in 2020 were collected. The average age of the patients was 58.8 ± 15.9 years. Among the 283 patients, 162 (57.6%) were male, 79 patients (27.9%) had pulmonary embolism, 102 patients (36%) were smokers, and 107 patients (37.8%) had a history of hypertension. A significant relationship was observed between the occurrence of pulmonary embolism and elevated levels of, white blood cells (WBC) (P = 0.0001), lactate dehydrogenase (LDH) (P = 0.0001), D-dimer (P = 0.0001), polymorphonuclear neutrophils (PMN) (P = 0.020), lymphocytes (P = 0.013), alkaline phosphatase (Alk.P) (P = 0.025), alanine aminotransferase (ALT) (P = 0.019), and aspartate aminotransferase (AST) (P = 0.017). Conclusions: Based on the results of this study, the incidence of pulmonary embolism in hospitalized COVID-19 patients who underwent CT angiography due to clinical suspicion of thrombosis was 27.9%. Additionally, factors such as smoking, a previous history of pulmonary thromboembolism, high WBC, elevated liver function tests (LFT), and elevated LDH levels were identified as risk factors for the occurrence of pulmonary embolism in these patients.