High-throughput single-cell omics of non-human primate (NHP) brain tissue provide a powerful platform to investigate the molecular basis of brain aging. Here, we present a comprehensive transcriptomic and chromatin accessibility atlas of 2,955,873 cells from eight brain regions of 23 female cynomolgus macaques spanning the adult lifespan, including exceptionally old individuals. Our analyses reveal dynamic, cell-subtype- and region-specific age-related changes in core brain functions, including synaptic communication and axon myelination. We identify multicellular networks in the pons and medulla as a previously unrecognized hotspot of primate brain aging, highlighting white matter vulnerability as a central feature of aging. Integration with human brain aging and neurodegeneration datasets reveal both shared and distinct molecular mechanisms. We further define transcription factors and age-related chromatin remodeling programs linked to longevity and neurodegeneration. This spatiotemporal atlas establishes a foundational framework for understanding the cellular and regulatory architecture of primate brain aging and its links to disease.