Sunn hemp (Crotalaria juncea L.) is a versatile crop grown widely for its fiber, green manure, fodder, and biofuel purposes. It is a leguminous crop of Indian origin and is cultivated in tropical and sub-tropical regions worldwide. Prior to the Green Revolution, sunn hemp was a significant fiber crop in the rural economy. However, it has since been supplanted by staple crops. Currently, sunn hemp is being cultivated on marginal lands with limited resources during the summer season. The development of improved cultivars for various uses has been hindered by a lack of comprehensive understanding of germplasm, including related and wild species. Additionally, there is a shortage of genetic information on breeding patterns and the gene functions that control different yield traits in sunn hemp, which has further slowed progress. New research has brought to light the breeding behavior of sunn hemp and has explored its diversity to some extent. However, conventional breeding techniques face difficulties in developing improved cultivars due to the crop’s complex breeding behavior. Advancements in modern breeding tools such as transgenics, genomics, transcriptomics and gene editing techniques offer a potential solution to overcome the limitations of conventional techniques and pave the way for the development of improved cultivars. Sunn hemp has recently gained significant attention, with numerous studies and ongoing efforts focused on developing high-yielding varieties to promote sustainable agricultural production. This chapter outlines the challenges related to the biodiversity and conservation of sunn hemp germplasm, as well as its floral biology, breeding systems, and pollination mechanisms. It also discusses the goals and phases of breeding programs, alongside traditional breeding methods. Furthermore, the chapter delves into the impact of polyploidization, mutation breeding, molecular breeding, genetic engineering, and gene editing techniques on enhancing sunn hemp crops.