Composites based on polypropylene (iPP) modified with a sorbitol derivative (NX8000) and siloxane-silsesquioxane resin (SiOPh-2) containing maleated polypropylene (MAPP) as compatibilizer were prepared by melt extrusion. Calorimetric investigations were carried out using Differential Scanning Calorimetry (DSC), whereas the morphological and mechanical properties were investigated by Scanning Electron Microscopy (SEM) and static tensile tests. Moreover, the oscillatory rheological measurements were performed to examine crystallization behavior under shearing conditions. DSC measurements revealed no influence of SiOPh-2 and MAPP addition on the crystallization kinetics of polypropylene. The introduction of MAPP into the iPP+NX8000+SiOPh-2 composites reduced stiffness and increased plastic properties of the samples. Moreover, rheological investigations revealed a shift in dynamic viscosity increase towards lower temperatures. All the above was attributed to the compatibilizing effect of MAPP, which improved interfacial adhesion between iPP, NX8000 and SiOPh-2. This phenomenon was also confirmed by the SEM images illustrating more homogenous distribution of the filler in the compatibilized samples.