<p>Atherosclerosis is the underlying cause of cardiovascular disease. Recent studies have shown that <i>N</i>⁶-methyladenosine (m⁶A) modification in macrophages is associated with atherosclerosis progression. However, there is a lack of systemic research on the role of m⁶A modification in macrophage differentiation and activation during atherosclerosis. Here we conducted multiomics analysis (MeRIP-seq and RNA-seq) of macrophages during their differentiation and activation to elucidate the regulatory network of the m⁶A spectrum at different stages. Western blot, quantitative PCR (qPCR), RNA-seq and RNA immunoprecipitation (RIP)–qPCR results demonstrated that m⁶A modification modulates KDM6B expression during macrophage activation. Through co-immunoprecipitation, RIP‒qPCR and genetic perturbation experiments, we revealed that Mettl3/Rbm15 regulates the stability of <i>Kdm6b</i> mRNA and that Kdm6b is required for interacting with and demethylating Jak1 to induce its phosphorylation-mediated macrophage activation. Next, through the analysis of single-cell RNA-seq data and coculture experiments, we revealed that Kdm6b-mediated macrophage activation promoted cytotoxic T lymphocyte cytotoxicity following atherosclerosis progression. Moreover, the systemic use of STM2457, a METTL3 inhibitor, revealed the importance of m⁶A modification in immune cell infiltration and plaque activation. Finally, we utilized macrophage-specific <i>Kdm6b</i>-knockout mice to determine whether Kdm6b facilitates macrophage and cytotoxic T lymphocyte activation and atherosclerosis. Our findings revealed that m⁶A modification plays a pivotal role in the upregulation of Kdm6b in response to IFN-γ stimulation, which is essential for the phosphorylation of Stat1-induced macrophage activation-mediated atherosclerosis development.</p>