In this work, the frequency dependence of ferroelectric and electrocaloric properties in barium titanate-based ceramics was studied based on Maxwell relations. It is found that the maximum and remnant polarization will decrease while the coercive field increases a lot with rising frequency from 0.1 to 10$$Hz, indicating that polarization rotation and domain switching become difficult at high frequencies. The electrocaloric properties show the different frequency dependence at different phase structures. Isothermal entropy change ($\mathrm{\Delta }S$) and adiabatic temperature change ($\mathrm{\Delta }T$) are similar around/above Curie temperature ($T_C)$, showing tiny frequency dependence. However, $\mathrm{\Delta }S$ and $\mathrm{\Delta }T$ display the obvious frequency dependence below $T_C$, especially in the orthorhombic–tetragonal phase-transition region with a stable ferroelectric phase, and this frequency dependence becomes more obvious under a low-electric field. It is also found that increasing the frequency can weaken the electric field dependence of electrocaloric strength. This work gives a general profile of frequency dependence for electrocaloric properties in ferroelectric ceramics.