We report on high-statistics data from the β^- decay of the ⁴⁶K J^π = 2^- ground state taken with the GRIFFIN spectrometer located at the TRIUMF-ISAC facility. In total, 199 γ rays and 42 excited states were placed in the level scheme, and from the observed β feeding and angular correlations of pairs of cascading γ rays, it was possible to assign spins and parities to excited states and determine mixing ratios for selected γ rays. The level structure of ⁴⁶Ca is compared to theoretical predictions from a microscopic valence-space Hamiltonian derived from two- and three-nucleon forces. These calculations are in reasonable agreement with the experimental data and indicate that the protons in this region are not as inert as would be expected for semimagic nuclei.