In this paper, a metal-dielectric metamaterial absorber is proposed to achieve ultrabroadband absorption at frequencies from ultraviolet to near-infrared. Based on finite element method solutions, the average absorption of the absorber is 97.75% from 382 nm to 1100 nm, with a maximum of 99.92%, resulting from multiple resonance coupling. The influences of geometric parameters and incident conditions on absorption are investigated. Broadband and narrowband absorption changes are realized by changing incident light polarization. Polarization-independent properties can be realized by changing the dielectric structure to centrosymmetric. The average absorption of the polarization-independent structure is 97.11% from 250 nm to 1115 nm, with a maximum of 99.98%. The proposed absorber structure has wide optical applications including solar energy harvesting and light-emitting devices.