An integrated magnonic device is a miniaturized system that manipulates magnons to perform computing, signal processing, or sensing functions. These devices leverage the wave-like nature of magnons to transmit and process information with low energy consumption. However, a major contemporary challenge lies in managing the reflections between cascaded magnonic devices during the design of two-dimensional integrated magnonic circuits. To address this issue, a magnonic directional coupler with non-reciprocal behavior has been developed using interfacial Dzyaloshinskii–Moriya interaction (iDMI). This design has been validated through micromagnetic simulations. The iDMI induces an asymmetric dispersion curve in the coupled waveguide, resulting in non-reciprocal coupling strength in the spin waves transmitted in the positive and negative directions. The non-reciprocal directional coupler effectively suppresses reflections along the original propagation path, functioning similarly to a circulator to isolate connected magnonic devices. This advancement represents a significant step forward in the development of robust and scalable spin-wave computing systems.