This paper presents a joint decoding scheme for an overloaded multiple input multiple output (MIMO) -orthogonal frequency division multiplexing (OFDM) system. In the overloaded MIMO system the number of receive antenna elements is less than that of transmit antenna elements. It has been shown that under the overloaded condition the performance of joint detection deteriorates while diversity reduces the amount of performance degradation caused by signal multiplexing. Thus, this paper proposes a maximum likelihood joint decoding scheme of block coded signals in the overloaded MIMO-OFDM system. The performance of joint decoding over Rayleigh fading channels is evaluated through the experiments. It is shown that the diversity through block coding realizes a limited amount of performance degradation in joint decoding of 2 Hamming coded signal streams.