An apparatus and a method of correcting a mismatch of a time-interleaved analog-to-digital converter are provided. The apparatus may include: a time-interleaved analog-to-digital converter configured to receive a non-return-to-zero (NRZ) signal in a correction mode and generate a first output signal, and including a plurality of analog-to-digital converters; and a mismatch corrector configured to generate a second output signal by processing the first output signal of the time-interleaved analog-to-digital converter based on parameters, wherein the parameters may be generated based on the first output signal of the time-interleaved analog-to-digital converter in the correction mode, and a period of the NRZ signal may be different from a product of a sampling period of the time-interleaved analog-to-digital converter and a number of the plurality of analog-to-digital converters included in the time-interleaved analog-to-digital converter.