Abstract Background Sri Lanka’s health policies prioritize improving hypertension control. The care cascade framework, a valuable tool that has informed hypertension control strategy in many countries, has not been assessed previously in Sri Lanka. This study addresses this gap using data from a nationally representative, longitudinal cohort study, providing a baseline for future monitoring. Methods We analysed data from the 2018–2019 first wave of the Sri Lanka Health and Ageing Study (SLHAS). The extended care cascade included: (i) prevalence, (ii) ever screened, (iii) diagnosis, (iv) awareness, (v) treatment, (vi) adherence, and (vii) control. We used multivariate logistic regression to assess factors associated with attainment of each step, conditional on prevalence and on treatment, and we assessed socioeconomic inequalities using concentration indices. We also compared performance against global estimates, and against regional and middle-income countries. Results We included 6,342 participants in the analysis. The weighted prevalence of hypertension was 27.6%. Of those with hypertension, 87% had their blood pressure (BP) ever measured; 53% were diagnosed; 50% were aware of their condition; 44% were taking treatment; and 20% had their blood pressure under control. Females and older adults had better cascade outcomes, but this was driven by higher rates of diagnosis. Diabetes and increased body mass index (BMI) were associated with higher diagnosis rates, but not treatment and control after diagnosis. Education and sector of residence were not associated with disparities, but treatment rates were higher in the most socioeconomic advantaged. Concentration indices confirmed pro-rich inequality across the care cascade from ever screened to treatment and adherence, but control was not unequal, with the data suggesting better control by public providers, whom the poor relied on more. Conclusions Only one in five Sri Lankans with hypertension achieve BP control, with the biggest cascade losses occurring at diagnosis and control after treatment. Our findings point to a substantial influence of providers. Efforts to improve hypertension control in Sri Lanka should focus on increasing detection through opportunistic screening and improving interventions to improve physician control of BP. These findings provide actionable insights for further research and to strengthen hypertension control efforts in Sri Lanka.