Here, a new balanced-to-balanced filtering power divider with an arbitrary power division ratio is proposed by utilising the circular patch resonator. To clarify the working principle, the resonant property of the circular patch resonator is firstly investigated. A prototype of the balanced-to-balanced power divider with arbitrary power division ratio is then developed. This prototype consists of only one circular patch resonator, three pairs of balanced ports, and two ports terminated with matching impedances. With this simple arrangement, the desired performance of a balanced-to-balanced power divider with an arbitrary power division ratio can be satisfactorily achieved at the resonant frequency of TM. Afterwards, a second-order filtering circuit is constructed. In this context, two circular patches are arranged at the two sides of the ground and good signal transmission is realised by virtue of proper coupling apertures etched on the ground. Apart from coupling, the apertures can be further used for harmonic suppression. Therefore, this proposed structure not only has improved in-band and out-of-band performances, but also has good harmonic suppression. To verify the design concept, two balanced-to-balanced filtering power dividers with division ratios of 1:1 and 15:1 are finally designed and fabricated. All the measured results agree well with the simulated ones.