  Kagome metals are reported to exhibit remarkable properties, including
superconductivity, charge density wave order, and a large anomalous Hall
conductivity, which facilitate the implementation of spintronic devices. In
this work, we study a novel kagome metal based on Mn magnetic sites in a
KMn$_3$Sb$_5$ stoichiometry. By means of first-principles density functional
theory calculations, we demonstrate that the studied compound is dynamically
stable, locking the ferromagnetic order as the ground state configuration, thus
preventing the charge-density-wave state as reported in its vanadium-based
counterpart KV$_3$Sb$_5$. Our calculations predict that KMn$_3$Sb$_5$ exhibits
an out-of-plane (001) ferromagnetic response as the ground state, allowing for
the emergence of topologically protected Weyl nodes near the Fermi level and
nonzero anomalous Hall conductivity ($\sigma_{ij}$) in this centrosymmetric
system. We obtain a tangible $\sigma_{xy} = 314$ S$\cdot$cm$^{-1}$ component,
which is comparable to that of other kagome metals. Finally, we explore the
effect of the on-site Coulomb repulsion ($+U$) on the structural and electronic
properties and find that, although the lattice parameters and $\sigma_{xy}$
moderately vary with increasing $+U$, KMn$_3$Sb$_5$ stands as an ideal stable
ferromagnetic kagome metal with a large anomalous Hall conductivity response.
