As a representative example of the rapid urbanization process occurring in China, the flora of the Shanghai region has long been subjected to the dual pressure of intense human activities and natural ecosystems. However, insufficient quantitative analysis concerning the evolutionary mechanisms of the flora in this area, within the context of urbanization, limits the scientific development of urban biodiversity conservation strategies. This study, which integrates multi-source data, investigates the flora and biodiversity distribution patterns in Shanghai. Through comprehensive research on existing data, a total of 1 507 species of higher plants have been recorded, belonging to 171 families and 779 genera. The statistical analysis of plant families indicates that Gramineae and Compositae are the primary contributing groups to species diversity, each comprising more than 100 plant species. At the genus-level statistical analysis, Carex and Polygonum emerged as large genera, each containing between 15 and 29 plant species. The examination of the geographical components of the flora revealed that the flora of Shanghai is predominantly composed of temperate plants, with a certain degree of tropical influence. In terms of plant life forms, herbaceous plants are the most prevalent. Through cluster and correspondence analysis, the flora of Shanghai was divided into 10 evaluation units, and their life forms were analyzed. From the perspective of ecological types, the flora of Shanghai can mainly be classified into coniferous forests, broad-leaved forests, bamboo forests, marshes, and aquatic vegetation, as well as coastal meadows. This study aims to systematically investigate the plant diversity and its distribution patterns in Shanghai, fill existing research gaps in this field, and provide a scientific basis for the management and sustainable use of biodiversity in urban environments.