The typical coarse resolution of Earth system models (ESMs) ($\sim$100 km) is insufficient to represent atmospheric features critical for aerosols and aerosol-cloud interactions (ACI), contributing to uncertainties in climate predictions. Significant efforts have been made to develop next-generation ESMs for global kilometer-scale resolutions. However, the behavior of aerosol and ACI parameterizations at kilometer scales within a global ESM framework is unclear, and model evaluation at such high resolutions is computationally infeasible. To address this challenge, aerosol and ACI in the Energy Exascale Earth System Model (E3SM) are evaluated at a convection-permitting 3.25 km resolution using the regionally refined mesh (RRM) capability. Kilometer-scale E3SM simulations are performed in four geographical regions with distinct aerosol and cloud conditions. These kilometer-scale simulations are compared with coarse-resolution E3SM simulations and are evaluated against ground-based, aircraft, and satellite measurements. Results show that increasing model resolution moderately improves the multivariable relationships related to ACI, such as the cloud condensation nuclei number versus cloud droplet number (N$\mathrm{_d}$), and N$\mathrm{_d}$ versus the liquid water path. However, its impact on accurately predicting aerosol properties varies by region. Overall, the differences between E3SM simulations at different resolutions are smaller than the differences between model simulations and observations. These results suggest that increasing resolution is insufficient to improve the simulation of aerosol and ACI with existing process representations. Improved process representations are required to achieve more accurate simulations of aerosol and ACI at global kilometer scales.