This article presents the 2021 cancer statistics in Korea, including incidence, mortality, survival, and prevalence. The number of new cancer diagnoses in 2021 increased by 10.8% compared to 2020, reaching 277,523 cases, with an age-standardized rate of 289.3 per 100,000. Cancer mortality in 2021 was 82,688 cases, with an age-standardized rate of 67.6 per 100,000. Cancer incidence rates increased until 2012, then decreased until 2015, with no significant changes afterward. Cancer mortality rates have been decreasing since 2002, with a faster decline in recent years. The 5-year relative survival rate for cancer patients between 2017 and 2021 was 72.1%, contributing to over 2.4 million prevalent cases in 2021. The number of new cancer cases increased in 2021 as healthcare utilization recovered from the declines caused by the COVID-19 pandemic. Revised cancer registration guidelines expanded the scope of registration, particularly for stomach and colorectal cancer. Survival rates have improved over the years, leading to a growing population of cancer survivors, necessitating a comprehensive cancer control strategy. The long-term impact of the pandemic on cancer statistics requires further investigation. The study highlights the importance of continued cancer control efforts to address the increasing number of cancer cases and survivors.This article presents the 2021 cancer statistics in Korea, including incidence, mortality, survival, and prevalence. The number of new cancer diagnoses in 2021 increased by 10.8% compared to 2020, reaching 277,523 cases, with an age-standardized rate of 289.3 per 100,000. Cancer mortality in 2021 was 82,688 cases, with an age-standardized rate of 67.6 per 100,000. Cancer incidence rates increased until 2012, then decreased until 2015, with no significant changes afterward. Cancer mortality rates have been decreasing since 2002, with a faster decline in recent years. The 5-year relative survival rate for cancer patients between 2017 and 2021 was 72.1%, contributing to over 2.4 million prevalent cases in 2021. The number of new cancer cases increased in 2021 as healthcare utilization recovered from the declines caused by the COVID-19 pandemic. Revised cancer registration guidelines expanded the scope of registration, particularly for stomach and colorectal cancer. Survival rates have improved over the years, leading to a growing population of cancer survivors, necessitating a comprehensive cancer control strategy. The long-term impact of the pandemic on cancer statistics requires further investigation. The study highlights the importance of continued cancer control efforts to address the increasing number of cancer cases and survivors.