Relay cropping is a multiple cropping method in which one crop is seeded into a standing second crop before the second crop is harvested. Relay cropping has the potential to resolve a variety of conflicts, such as inefficient resource use, disagreements over sowing time, fertilizer application, and soil degradation. Relay cropping is a complex set of resource-efficient technologies that can improve soil quality, increase net return, increase land equivalent ratio, and control weed and pest infestations. Grass pea is well-known as one of the most resilient and versatile crops, capable of thriving in extreme climatic conditions such as cold, heat, drought, salt-affected soils, submergence, and excessive rainfall, as well as resistance to a variety of diseases and pests. The current review focused on relay cropping as a tool for crop diversification and environmental sustainability, with a specific emphasis on different grass pea cultivars relaying with T. aman rice in the Jamalpur region during 2019-2020 and 2020-2021. The highest rice equivalent yield was produced by grass pea var. BARI Khesari-3 relayed with T. aman rice cultivation, followed by grass pea Jamalpur Local relayed with T. aman rice cultivation. In addition, the highest gross return, net return, and benefit cost ratio were all attained. As a result, rice-based grass pea relay cropping systems have been shown to be more profitable and sustainable than sole cropping systems. As a result of proper utilization and minimizing the time of grass pea production which fits well to produce valuable boro rice production in the following crop.