INTRODUCTION: The experience gained from managing the first wave of the pandemic, combined with the abundance of scientific evidence, enabled physicians to identify risk factors for mortality outcomes and evaluate the effectiveness of respiratory support measures, vaccines, and drugs. This knowledge empowered them to confront the subsequent waves with greater expertise. Despite these advancements, the mortality rate among critical COVID-19 patients remained alarmingly high worldwide during these waves. It is uncertain whether advancements in critical care during the pandemic have improved outcomes for critically ill COVID-19 pneumonia patients admitted to the intensive care units (ICUs). METHODS: This was an observational, retrospective cohort study utilizing the collected data from COVID-19 patients between May to July 2020 and May to July 2021 at the Medical Records Department (MRD) section of BGS Global Institute of Medical Sciences Hospital, Bangalore, Karnataka. RESULTS: The mortality rate was higher among males in 2020 (66.1%) and 2021 (65.7%) compared to females in 2020 (33.9%) and 2021 (34.3%), with males accounting for nearly double the proportion of deaths in both waves. In 2020, the highest mortality was observed in the age group of 41-50 years (27.1%), while in 2021, it was noted in the age group of 51-60 years (24.3%). Altogether, patients in the age group of 41-60 years were the ones who were mostly affected in both waves. The average hospital stay increased from 3.8 days in the first wave to 7.4 days in the second. Diagnosis of COVID-19 pneumonia with comorbidities while being admitted into the ICUs accounted for 11.5% of cases in the first wave, rising to 68.6% in the second wave. Cause of death solely due to type 1 respiratory failure and acute respiratory distress syndrome was reported in 92.3% of cases in 2020 and 70.7% in 2021. In contrast, other non-respiratory causes contributed to 7.7% of deaths in 2020 and 29.3% in 2021. CONCLUSION: This study provides insights into the ICU mortality trends in critically ill COVID-19 pneumonia patients during the first and second waves of the global pandemic. Despite advancements in disease knowledge, treatment protocols, and healthcare system management, no significant improvement in the mortality rates was found in our study. The mutations of the virus, which enhanced its transmissibility and immune escape characteristics, greatly contributed to our findings. Adoption of stringent social distancing, regular screening, early reporting of symptoms by the patient, well-established isolation, strict adherence to standard operating procedures (SOPs), and health advisory guidelines reduced ICU occupancy by patients diagnosed with COVID-19 pneumonia only, making room for complex cases to receive adequate timely care and treatment during the second wave. Limitations of the study include its single-center study design, missing data, and lack of post-vaccination data, all of which must be duly considered.