We report muon spin rotation (µSR) experiments on the microscopic properties of superconductivity and magnetism in the kagome superconductor CeRu2 with K. From the measurements of the temperature-dependent magnetic penetration depth λ, the superconducting order parameter exhibits nodeless pairing, which fits best to an anisotropic s-wave gap symmetry. We further show that the /λ −2 ratio is comparable to that of unconventional superconductors. Furthermore, the powerful combination of zero-field (ZF)-µSR and high-field µSR has been used to uncover magnetic responses across three characteristic temperatures, identified as K, K, and K. Our experiments classify CeRu2 as an exceedingly rare nodeless magnetic kagome superconductor.