A method for performing channel shortening equalization with frequency notch mitigation is provided, where the method is applied to an electronic device. The method includes: obtaining channel response information from channel estimation to determine a relaxed channel convolution matrix corresponding to the channel response information, with the relaxed channel convolution matrix being a partial matrix of a channel convolution matrix corresponding to the channel response information, wherein the relaxed channel convolution matrix is obtained from omitting a portion of matrix elements of the channel convolution matrix; and based upon the relaxed channel convolution matrix, jointly performing time domain channel shortening control and frequency domain flatness control over the TEQ to perform channel shortening equalization with frequency notch mitigation by utilizing the TEQ. In particular, the portion of matrix elements includes a plurality of rows of matrix elements within the channel convolution matrix. An associated apparatus is also provided.