We study some necessary and sufficient conditions for the boundedness of the Riesz potential operator \(I_{\alpha }\) and its commutator on the total Morrey spaces \(L_{p,\lambda ,\mu }(\mathbb {R}^n)\) . We characterize the strong and weak Spanne type and Adams type boundedness of \(I_{\alpha }\) on \(L_{p,\lambda ,\mu }(\mathbb {R}^n)\) , respectively. We also give necessary and sufficient conditions for the boundedness of the commutator of the Riesz potential operator \([b,I_{\alpha }]\) on \(L_{p,\lambda ,\mu }(\mathbb {R}^n)\) when b belongs to the spaces \(BMO(\mathbb {R}^n)\) . As applications, we obtain some estimates for the Marcinkiewicz operator and fractional powers of some analytic semigroups on the total Morrey spaces.