Objectives: This study aimed to assess the rate of concordance, and to investigate sources of non-concordance of recommendations in the management of hypertension across CPGs in Southeast Asia, with internationally reputable clinical practice guidelines (CPGs). Methods: CPGs for the management of hypertension in Southeast Asia were retrieved from the websites of the Ministry of Health or cardiovascular specialty societies of the individual countries of Southeast Asia during November to December 2020. The recommendations for the management of hypertension specified in the 2017 American College of Cardiology (ACC)/American Heart Association (AHA) guideline and the 2018 European Society of Cardiology (ESC)/European Society of Hypertension (ESH) guideline were selected to be the reference standards; the recommendations concerning the management of hypertension in the included CPGs in Southeast Asia were assessed if they were concordant with the reference recommendations generated from both the 2017 ACC/AHA guideline and the 2018 ESC/ESH guideline, using the population (P)-intervention (I)-comparison (C) combinations approach. Results: A total of 59 reference recommendations with unique and unambiguous P-I-C specifications was generated from the 2017 ACC/AHA guideline. In addition, a total of 51 reference recommendations with unique and unambiguous P-I-C specifications was generated from the 2018 ESC/ESH guideline. Considering the six included CPGs from Southeast Asia, concordance was observed for 30 reference recommendations (50.8%) out of 59 reference recommendations generated from the 2017 ACC/AHA guideline and for 31 reference recommendations (69.8%) out of 51 reference recommendations derived from the 2018 ESC/ESH guideline. Conclusions: Hypertension represents a significant issue that places health and economic strains in Southeast Asia and demands guideline-based care, yet CPGs in Southeast Asia have a high rate of non-concordance with internationally reputable CPGs. Concordant recommendations could perhaps be considered a standard of care for hypertension management in the Southeast Asia region.