This study presents the design and realization of a dual-port multiple-input–multiple-output (MIMO) filtering antenna system. The device shows good response in the frequency rage 1 (4.1 to 7.125 GHZ) frequency band, which handles most of the cellular mobile communication traffic. First, the single element ultra-wideband (UWB) filtenna is designed by combining a UWB antenna and a band-reject filter (BRF) where the antenna works in the frequency range from 1 to 11 GHz and the BRF is rejecting the frequency range of 3–3.42 GHz with 3.2 GHz as its resonant frequency. Finally, the proposed two-port MIMO filtenna combines two single element UWB filtennas in antiparallel manner which shows impedance bandwidth from 2.59 to 7.1 GHz with a band notch from 3 to 3.42 GHz. The structure is built on cost-efficient FR4 substrate (εr = 4.4, tanδ = 0.02) of dimensions 0.68${{\boldsymbol{\lambda }}_{\boldsymbol{c}}}$×0.27${{\boldsymbol{\lambda }}_{\boldsymbol{c}}}$×0.01${{\boldsymbol{\lambda }}_{\boldsymbol{c}}}$ (mm3), which is compact in size and utilizes a defected ground structure for further miniaturization. The proposed design is simulated using Ansys HFSS software, and after fabrication, it is measured, and the output shows good results for the proposed application. The designed antenna system is suitable for fifth-generation (5G) wideband systems.