The multiplexer is a combinational circuit that transfers multiple data inputs over a single output line. The input data are selected and transferred to the output line based on the selection line. In this work, 2 × 1 and 4 × 1 multiplexer is proposed. The proposed multiplexer has been worked out using the electro-optic principle. It is implemented using lithium niobate-based Mach–Zehnder interferometer (LN-MZI). LN-MZI is used as an optical switching device. The performance parameters extinction ratio, contrast ratio and insertion loss have been computed and found 31.31, 28.02 and 0.043 dB respectively.