This work provides an exact analytical dynamics of a cantilever beam bonded with a piezoelectric patch to extract the modal frequencies under open circuit and short circuit electrodes’ conditions. The modal open circuit and short circuit frequencies are then used to calculate the corresponding modal Electro-Mechanical Coupling Coefficient (EMCC), which is considered as an influential parameter in the design of piezoelectric based devices such as energy harvesters and smart structures. A parametric analysis is then performed to optimize the length and the thickness of the piezoelectric patch for maximum modal EMCC.