This paper presents a low-power MMSE MIMO detector using a dynamic voltage wordlength scaling (DVWS) technique for 4×4 MIMO-OFDM systems. A MIMO MMSE detector requests high performance computing for real-time processing. A pipelined MMSE detector using Strassen's algorithm has been developed in our previous work. However, it consumes significant power and thus, we have to consider a low-power solution to minimize power dissipation. We propose a DVWS MIMO detector which changes a wordlength and a supply voltage simultaneously with fixed clock frequency. The proposed technique can keep fixed throughput unlike dynamic voltage frequency scaling (DVFS). The power result of the DVWS MMSE detector ranged from 232 to 717 mW depending on communication situations.