Arterial aging is a major risk factor for cardiovascular disease and is associated with progressive changes in vascular structure and function, including arterial stiffening, reduced elasticity, extracellular matrix remodeling, chronic low-grade inflammation, and accumulation of senescence-associated cell states. Recent advances in single-cell RNA sequencing (scRNA-seq) have provided new opportunities to resolve the cellular heterogeneity underlying these age-related alterations in the arterial wall. In this review, we summarize current single-cell studies of arterial aging by focusing first on key phenotypic programs, including cellular senescence, extracellular matrix remodeling, inflammaging, and altered intercellular communication, and then discuss how these programs are reflected in endothelial cells, smooth muscle cells, fibroblasts, and immune cells. Across studies, aging is recurrently associated with endothelial dysfunction, smooth muscle cell phenotypic modulation, fibroblast-related matrix remodeling, and immune activation, although the degree of conservation varies depending on species, vascular bed, sex, and disease context. We further discuss emerging evidence that vascular aging involves not only cell-intrinsic transcriptional changes but also alterations in communication networks across the arterial wall. Although current single-cell studies have substantially improved our understanding of arterial aging, important limitations remain, including inconsistent cell-state annotation across studies, incomplete functional validation, and limited spatial and epigenetic resolution. Future integration of cross-species analyses with spatial transcriptomics, single-cell epigenomic approaches, and functional studies will help refine the cellular framework of arterial aging and improve its translational relevance.