Timber-concrete composite panels, due to its benefits, are one of the most popular alternatives to common slabs of pure timber or concrete. In the analyse of load-carrying capacity for timber-concrete composite panels, subjected to flexure, the important component is connection system between concrete layer and timber, which affects the stress distribution and the deformations of the structure. Possibility to increase effectiveness of structural materials use and load-carrying capacity of the timber-concrete composite structural members, with the rigid timber to concrete joint, was evaluated in this research. Consequently, possibility to develop rigid timber to concrete joint by the using of the crushed granite pieces as the keys was checked by the experiment. Development of rigid timber to concrete joint enables to increase effectiveness of the structural materials use in timber-concrete composite panels in comparison with the compliant once. Behavior of the timber-concrete composite panels were analysed by the transformed section method, finite element method and by experiment for the purpose of this study. Four timber-concrete composite panels were statically loaded till the failure by the scheme of three-point bending. Variants of composite panels with the rigid and combined timber-concrete joints were investigated. The rigid timber-concrete joint was provided by the pieces of crushed granite, which were strengthened on the surface of the timber boards by epoxy glue. Dimensions of the crushed granite pieces changes within the limits from 16 to 25 mm. Moreover, the combined timber-concrete joint was provided by the screws and by the crushed granite pieces. The screws were placed under the angles equal to 45 degrees relatively to the direction of fibres of the timber layers in accordance with the literature recommendations. As a result, it was stated, that load–carrying capacity of timber-concrete composite panels is up to 1.9 times higher than the same of cross-laminated timber panels. The maximum load-carrying capacity in 43 kN was obtained for the variant of timber-concrete composite panel with the rigid timber to concrete joint at the same time.