We demonstrate a self-interference (SI) cancellation in cooperative multiple-input multiple-output (Co-MIMO) for full-duplex (FD) wireless communication systems by applying the block diagonalization used in multi-user MIMO. The proposed method's implementation uses a field-programmable gate array (FPGA) and software-defined radio (SDR). In the experiment, a total of 30 [dB] SI can cancel with two cooperative APs and two antennas per AP in the IEEE 802.11 system.