Multiple-input multiple-output (MIMO) technology can be used in orthogonal frequency division multiplexing (OFDM) systems to improve communication quality and capacity. In this paper, we develop a blind channel estimation method based on a subspace approach for MIMO-OFDM systems. The proposed method obtains accurate channel estimation by utilizing a non-redundant linear precoder at the transmitter and it is insensitive to the overestimates of the channel order. Our method can be applied for MIMO systems with any number of transmitter or receiver antennas. The numerical results are provided to illustrate the effectiveness of the proposed blind channel estimation method.