Background and Objectives <p>Colorectal cancer (CRC) remains a significant cause of cancer-related morbidity and mortality in East Asia. The absolute burden is increasing rapidly, driven largely by demographic change, and varies substantially across countries. However, the extent to which long-term trends, population ageing, and socioeconomic development jointly shape the regional CRC burden has not yet been fully quantified. The objective of the present study is to characterise temporal trends and age-specific patterns in CRC burden, in addition to quantifying the contributions of key drivers of change.</p> Methods <p>This study is a population-based observational analysis using estimates from the Global Burden of Disease (GBD) 2023 study, covering China, Japan, Mongolia, the Democratic People’s Republic of Korea, and the Republic of Korea from 1990 to 2023. We analyzed incident cases, prevalent cases, deaths, and disability-adjusted life years (DALYs). Age-standardized incidence, prevalence, mortality, and DALY rates were calculated, and their associations with the Socio-demographic Index (SDI) were assessed using Spearman correlation with non-linear curve fitting. Changes in absolute burden were decomposed into contributions from population growth, population ageing, and epidemiological change. Future trends of age-standardized rates to 2050 were projected using autoregressive integrated moving average (ARIMA) models, and temporal changes in mortality trends were evaluated using joinpoint regression.</p> Results <p>From 1990 to 2023, the absolute numbers of incident cases, prevalent cases, deaths, and DALYs from CRC increased across all countries, while trends in age-standardized rates diverged. The age-standardized incidence rate increased markedly in the Republic of Korea (22.98 to 37.78 per 100,000; EAPC 1.71%) and the Democratic People’s Republic of Korea (13.88 to 22.60 per 100,000; EAPC 1.48%), with more moderate increases in China and Japan and a slight decline in Mongolia. The age-standardized prevalence rate rose substantially, particularly in the Republic of Korea (96.07 to 224.73 per 100,000; EAPC 3.01%). In contrast, age-standardized mortality and DALY rates declined in most countries but increased in the Democratic People’s Republic of Korea. The burden increased steeply with age, especially after 50 years. Significant positive correlations were observed between SDI and all age-standardized rates (ρ = 0.843–0.748, all <i>p</i> &lt; 0.001), with non-linear patterns at higher SDI levels. Decomposition analysis identified population ageing as the primary driver of increasing burden. Projections indicate that the burden will remain high or continue to rise modestly through 2050, with increasing uncertainty. Joinpoint analysis revealed declining mortality trends in China, Japan, and the Republic of Korea, persistent increases in the Democratic People’s Republic of Korea, and a recent upturn in Mongolia.</p> Conclusions <p>The prevailing burden of non-communicable diseases in East Asia is characterised by an increase in the absolute number of cases, despite concurrent improvements or stabilisation in mortality and DALY rates in several settings. This phenomenon is predominantly driven by population ageing. The presence of strong SDI gradients and adverse trends in the DPRK underscores the necessity for customised strategies, encompassing risk-factor management, equitable expansion of screening programmes, and the augmentation of treatment capacity, with a particular emphasis on adults aged ≥ 50 years, to alleviate the anticipated future burden.</p>