The Kangchenjunga Landscape (KL) in the Eastern Himalayas is a transboundary complex shared by Bhutan, India, and Nepal. It forms a part of the 'Himalayan Biodiversity Hotspot' and is one of the biologically richest landscapes in the Eastern Himalayas. In this paper, we use secondary information to review and consolidate the knowledge on the flora of the KL. We reviewed 215 journal articles, analysed the history of publications on the flora of the KL, their publication pattern in terms of temporal and spatial distribution and key research areas. Our review shows that the landscape has a long history of botanical research that dates back to the 1840s and progressed remarkably after the 1980s. Most of the studies have been carried out in India, followed by Nepal and Bhutan. The majority of these have been vegetation surveys, followed by research on ethnobotanical aspects and Non-Timber Forest Products (NTFPs). This paper describes the forest types and characteristic species of the KL and details the species richness, diversity and dominant families of seed plants. A total of 5198 species of seed plants belonging to 1548 genera and 216 families have been recorded from the landscape, including 3860 dicots, 1315 monocots and 23 gymnosperms. Among families, Orchidaceae is the most diversely represented family in terms of species richness. This paper also draws attention to the threatened and endemic flora of the KL, including 44 species that are threatened at national and global level and 182 species that are endemic. Finally, the paper reviews the major challenges facing the KL, the conservation efforts and practices that are currently in place and recommends systematic and comprehensive floral surveys, particularly long-term data collection and monitoring and transboundary collaboration, to address the existing knowledge gaps on floral diversity of the KL.