Greville’s spectral \(\{1,2,3\}\) -inverses of a square complex matrix A are solutions to the four matrix equations \(AXA=A\) , \(XAX=X\) , \((AX)^{*}=AX\) and \(XA^{k+1}=A^{k}\) (for some integer \(k \ge 0\) ), possessing remarkable least-squares and spectral properties. In this paper, we give a canonical form of spectral \(\{1,2,3\}\) -inverses under the core-EP decomposition, which suggests a special kind of spectral \(\{1,2,3\}\) -inverse. We develop the main properties and characterizations of this special generalized inverse and show its applications in minimization problems of some linear systems.