This letter presents system implementation and validation of a real-time experimental ultrawideband (UWB) multiple-input–multiple-output (MIMO) radio testbed built at Tennessee Technological University, Cookeville. The incorporation of UWB technology with MIMO is promising in both communication and sensing applications. With the testbed, UWB MIMO algorithms are able to be experimentally explored by transmitting data through 500-MHz-bandwidth channels simultaneously supporting two transmit and eight receive antennas. Using a 2 2 MIMO time-reversal (TiR) configuration as an example, 6-dB gain over a single-input–single-output (SISO) configuration is experimentally achieved, agreeing with theoretical estimation. In particular, signal-to-intersymbol-interference (ISI) ratio (SIR), a performance metric common to many real-world applications, is experimentally evaluated with BPSK modulation. The obtained SIR results suggest that the UWB MIMO-TiR is promising for high data rate transmission in harsh RF environments.