Introduction: Coronavirus disease 2019 (COVID-19) pneumonia is heterogeneous disease with variable effect on lung parenchyma, airways, and vasculature, leading to long.term effects on lung functions. Robust data of ferritin in bacterial infection are available, and now its role as an inflammatory marker in COVID-19 pneumonia during initial assessment and planning of treatment is evolving. Materials and Methods: Prospective, two.center, observational study conducted from July 2020 to May 2021, in MIMSR Medical College and Venkatesh Hospital Latur, India, included 1000 COVID-19 cases confirmed with reverse transcription.polymerase chain reaction. All cases were assessed with lung involvement documented and categorized on high.resolution computed tomography (CT) of the thorax, oxygen saturation, inflammatory marker, Ferritin at the entry point, and follow.up during hospitalization. Age, gender, comorbidity, and use BIPAP (bi-level positive airway pressure)/NIV (noninvasive ventilation) (BIPAP/NIV) and outcome with or without lung fibrosis as per CT severity were key observations. CT severity scoring was done as per universally accepted standard scoring tool as score <7 as mild, 7.14 as moderate, and score > 15 as severe affection of lung. Statistical analysis is performed using Chi.square test. Results: Age (<50 and > 50 years) and gender (male versus female) have significant association with ferritin in predicting severity of COVID 19 pneumonia (P < 0.00001) and (P < 0.010), respectively. CT severity score at the entry point with ferritin level has a significant association (P < 0.00001). Ferritin level has a significant association with the duration of illness (P < 0.00001). Comorbidities have a significant association with normal and abnormal ferritin levels, respectively (P < 0.00001). Ferritin level has a significant association with oxygen saturation (P < 0.00001). BIPAP/NIV requirement during treatment in critical care settings has a significant association with ferritin level (P < 0.00001). Timing of BIPAP/NIV requirement during the course of COVID-19 pneumonia in critical care settings has a significant association with ferritin level (P < 0.00001). Follow.up ferritin titer during hospitalization as compared to entry point normal and abnormal ferritin has a significant association in post-COVID lung fibrosis, respectively (P < 0.00001). Conclusions: Ferritin is easily available, sensitive, reliable, cost.effective, and universally acceptable inflammatory marker in COVID-19 pneumonia. Ferritin has a very crucial role in COVID-19 pneumonia in predicting the severity of illness and assessing response to treatment during hospitalization. Follow.up ferritin titer during hospitalization and at discharge can be used as early predictor of post-COVID lung fibrosis.