The　nickel　element　doped　holmium　oxide　(Ho2O3:Ni)　transparent　magneto-optical　ceramics　were　fabricated　by　vacuum　sintering　and　the　dopant　impacts　on　structure　features　and　Faraday　effects　were　investigated.　The　starting　oxide　powders　were　synthesized　by　pyrolyzing　the　resulting　layered　holmium-based　hydroxide　nanosheets　prepared　from　a　chemical　precipitation　route　using　the　sodium　hydroxide　as　precipitant　at　the　freezing　temperature.　Upon　high-temperature　sintering,　the　(Formula　presented.)　defect　is　introduced　by　Ni2+　substitution　for　Ho3+　to　form　the　interstitial　solid　solution.　The　1　at.%　Ni2+　doped　Ho2O3　ceramic　sample　exhibits　an　in-line　transmittance　of　∼70.04%　at　1　550 nm　with　a　relative　density　of　∼99.88%,　while　more　Ni2+　incorporation　(e.g.,　2‒5　at.%)　even　leads　to　a　completely　opaque　state.　The　magneto-optical　transparent　Ho2O3:1%Ni　ceramic　developed　in　this　work　has　Verdet　constants　of　∼−195,　−65,　and　−29 rad/(T·m)　at　635,　1　064,　and　1　550 nm,　respectively,　which　are　∼1.8-fold　higher　than　the　commercial　terbium　gallium　garnet　crystal　or　∼1.4-fold　higher　than　the　pure　Ho2O3　ceramic.　This　material　also　possesses　relatively　large　figure　of　merit　of　∼14.6°/T　at　1　064 nm　and　relatively　high　thermal　conductivity　of　∼7.5 W/(m·K)　at　room　temperature.　©　2024　The　American　Ceramic　Society.