Dielectrostriction is a rheo-dielectric phenomenon, which reflects the variation of dielectric properties of a material with deformation. It is a fundamental property of any dielectric material, including polymers and many foods. A linear relationship has been found between the change in the dielectric constants and stresses for polymers and a chocolate spread, which is named the stress-dielectric rule. This study explored the dielectrostriction responses in three types of dark chocolate with different compositions in an oscillatory shear flow. The results revealed that the stress-dielectric rule holds well for all three types of chocolate, and the dielectrostricive response is much more sensitive than the rheological response to changes in the chocolate composition. These findings suggested that dielectrostriction measurements are a novel approach for rheological property studies, and can be developed into a powerful tool for chocolate process monitoring.