A novel 16-bit flexible Application-Specific Instruction-set Processor for an MMSE-IC Linear Equalizer, used in iterative turbo receiver, is presented in this paper. The proposed ASIP has an SIMD architecture with a specialized instruction-set and 7-stage pipeline control. It supports diverse requirements of MIMO-OFDM wireless standards such as use of QPSK, 16-QAM and 64-QAM modulation in 2×2 and 4×4 spatially multiplexed MIMO-OFDM environment. For these various operational modes, analysis of MMSE-IC LE equations and corresponding complex data representations was conducted. Efficient computational and storage resource sharing is proposed through: (1) Matrix Register Banks (MRB) multiplexing, (2) 16-bit Complex Arithmetic Unit (CAU) comprised of 4 complex and 2 real multipliers, 9 complex adders, and 6 complex subtractors, and (3) flexible 32-bit to 16-bit data conversion at multipliers’ output. With this architecture, the designed ASIP ensures, along with flexibility, high performance in terms of throughput and area. Logic synthesis results reveal a maximum clock frequency of 546 MHz and a total area of 0.37 mm2 using 90 nm technology. For 2×2 spatially multiplexed MIMO system, the proposed ASIP achieves a throughput of 273 Symbol/Sec.