A broadband eight-way differential substrate integrated waveguide (SIW) power divider with bandpass-filtering response by using novel hybrid multiple-via probe and multiple radial slots has been presented in this paper. The novel hybrid multiple-via probe are employed to achieve broadband impedance matching, while the multiple radial slots are used to improve the out-of-band rejection level. An eight-way differential SIW power divider with bandpass-filtering response is designed, fabricated, and measured. The measured results agree with the simulated ones closely in the desirable frequency range. The measured average insertion loss of the eight-way power divider is approximately 9.3 dB and input return loss is greater than 15 dB from 3.2 to 8.1 GHz. Moreover, the out-of-band rejection band with more than 25 dB attenuation from 9 GHz to more than 11 GHz is observed. A maximum amplitude imbalance of $$\pm 0.7\,\hbox { dB}$$ ± 0.7 dB is observed over the entire operating frequency range.