Hypertensive heart disease (HHD) and ischemic heart disease (IHD) are major global burdens. High body mass index (BMI) is a key modifiable risk factor, but the global burden, trends, and inequalities of HHD and IHD attributable to high BMI remain poorly defined. We analyzed Global Burden of Disease data from 1990 to 2021 across 204 countries, estimating age-standardized mortality rates (ASMRs), disability-adjusted life-year rates (ASDRs), and annual average percentage changes (AAPCs). Additional analyses included age- and sex-specific distributions, socio-demographic index (SDI) patterns, frontier and decomposition analyses, inequality metrics, and projections to 2035 using Bayesian age–period–cohort and ARIMA models. From 1990 to 2021, global ASMR and ASDR for HHD attributable to high BMI slightly increased (AAPC: 0.014 and 0.099), whereas those for IHD declined (AAPC: −0.067 and −0.751). The highest HHD burden occurred in Southern Sub-Saharan Africa, and the greatest IHD burden in Eastern Europe. Elderly females had higher HHD mortality and DALYs, while middle-aged males bore greater IHD burden. HHD inversely correlated with SDI (r = −0.5524, P < 0.001), whereas IHD showed a unimodal relationship. Decomposition highlighted aging and population growth as major contributors. Inequalities worsened for HHD but improved for IHD. Forecasts suggest continued rises in HHD and declines in IHD by 2035. HHD and IHD attributable to high BMI show divergent global trends and inequality patterns, underscoring the urgent need for targeted weight management and cardiovascular risk reduction, particularly in low- and middle-SDI regions.