In this study, we present an innovative Mars Ionosphere−Thermosphere Model (MITM), which is a time-dependent, three-dimensional (3-D) model that comprehensively represents the self-consistently coupled thermosphere and ionosphere of Mars within the altitude range of 70−300 km. The model incorporates an extensive range of parameters, including neutral number densities of CO2, CO, O, O2, N2, NO, N(2D), N(4S), Ar, and He; ion number densities of CO2+, CO+, O+, O2+, N2+, NO+, N+ ions, and electrons; neutral temperature; and neutral wind fields. The MITM code employs a high-resolution grid system in a spherical geographical coordinate system, with a horizontal resolution of 5° latitude by 7.5° longitude. This altitude-resolved grid system enables accurate depiction of spatial variations in the Martian thermosphere and ionosphere. To showcase the capabilities of the MITM, we present two simulation cases: one during the equinox and another during the solstice. Both simulations reproduce key features of the Martian thermosphere and ionosphere including the characteristics of horizontal circulation, diurnal variations in chemical composition, and distribution of electron density. The MITM offers a robust framework for understanding the intricate interactions and processes that shape the Mars thermosphere and ionosphere, which are crucial for enhancing our understanding of Martian upper atmosphere and ionosphere.