Our previous study uncovered that long-term abuse of caffeine sodium benzoate (CSB) could lead to dysfunction in human umbilical vein endothelial cells (HUVECs). However, the mechanism by which CSB induced endothelial dysfunction remains largely unstudied. CSB containing serum (CSB-CS) was collected from patients under long-term CSB inhalation. RAW264.7 cells were treated with different concentrations of CSB-CS, after which the conditioned medium (CM) was collected and cultured with HUVECs. The migration, tube formation, and senescence of HUVECs were evaluated. CSB-CS could induce polarization of RAW264.7 cells toward the M1 phenotype, as evidenced by the elevated CD86 and iNOS levels. Additionally, the CM from CSB-treated RAW264.7 cells notably suppressed the migration, tube formation, and induced cell senescence and endothelial dysfunction in HUVECs. Moreover, the CM from CSB-treated RAW264.7 cells greatly reduced mitochondrial membrane potential level, increased the ROS production, reduced OPA1 levels, but elevated DRP1 levels in HUVECs, leading to mitochondrial fission and dysfunction. Meanwhile, the CM from CSB-treated RAW264.7 cells remarkably reduced p-AKT and p-GSK3β levels in HUVECs. Notably, promotion of mitochondrial fusion by MASM7 could mitigate mitochondrial dysfunction and endothelial dysfunction in HUVECs induced by the CM from CSB-treated RAW264.7 cells. Collectively, we found that CSB could induce mitochondrial dysfunction in HUVECs by the polarization of pro-inflammatory M1 macrophages, resulting in endothelial dysfunction. These findings may provide a foundational basis for developing treatments for diseases associated with CSB.