Emerging 4G wireless standards require high-throughput low-complexity integration of digital baseband building blocks to realize MIMO receivers for high-order constellations and large antenna configurations. This paper presents a prototype of a high-throughput 4x4 64-QAM MIMO receiver consisting of a channel matrix QR decomposition, a soft-output K-Best MIMO detector and a Convolutional Turbo Code (CTC) decoder. The presented MIMO receiver provides low processing latency and a pipelined architecture that is scalable to a larger number of antennas and constellation orders. Thus, the presented MIMO receiver prototype is suitable for demanding signal processing requirements posed by LTE-Advanced and IEEE 802.16m broadband wireless standards. A rapid prototyping platform interfacing MATLAB with Xilinx ISE was used to implement the 4x4 64-QAM MIMO receiver. The optimized receiver occupies 64% of the slices on Virtex-5 FX130T FPGA and operates at a maximum frequency of 110MHz.