The design of two-degree-of-freedom vibration energy harvesters is necessary to enable the vibration energy harvesting for signals with two dominant vibration frequencies. This paper presents an analytical method for the design of piezoelectric cantilevers over two resonant frequencies. A two-degree of freedom (2-DOF) analytical model is proposed and exploited to provide general design guidelines: it enables the sizing of the proof mass to tailor the two resonant frequencies and the optimization of the electrodes’ dimensions to maximize the elec- tromechanical coupling coefficients k2 of the harvester at the resonances. Such high electromechanical coupling coefficients allow reaching the maximum power limit at the output of the vibration energy harvesters and, at high values of k2, to tune the resonant frequency using a dedicated electrical circuit (e.g., resistive tuning or non- linear circuit). A prototype of PZT-based cantilever has been designed and tested to validate the model. The prototype fea- tures two close resonant frequencies of 35.3 Hz and 53.2 Hz. When the electrodes are properly connected, the electromechanical coupling coefficient k2 reaches 10.4 % for the first mode and 8.7 % for the second mode, allowing for respective frequency bandwidths of 3 Hz (8.4 %) and 3.5 Hz (6.5 %) with resistive frequency tuning at 0.5 m/s2 acceleration. The maximum harvested power is 262 μW and 149 μW, respectively, for excitation frequencies matching the first and second resonances.