Geodiversity encompasses the diversity of abiotic materials, forms, and processes on and beneath the surface of the Earth. This study investigates the impact of geodiversity on biodiversity, shedding light on the interplay between subsurface-aboveground dynamics and geological-biological roles in natural ecosystems. Synthesizing domestic and international research, we explore the relationship between geodiversity and biodiversity, highlighting their joint role in maintaining natural ecosystems. Specifically, we focus on understanding the formation and maintenance mechanisms of high geodiversity supporting high biodiversity. Additionally, we examine the impact of geodiversity on biodiversity across various spatial scales, noting differences in effects at global, landscape, and local scales. We also underscore the lack of a unified understanding of the impacts of geodiversity on biodiversity and its driving mechanisms, particularly in protected areas. Furthermore, we summarize research methods for geodiversity assessment, including qualitative, quantitative, and qualitative-quantitative approaches, and highlight the effectiveness of the qualitative-quantitative method. Lastly, we suggest that future research should emphasize strengthening empirical analyses of geodiversity on biodiversity within nature reserves, integrating geodiversity on biodiversity research into the management of protected areas, and optimizing geodiversity assessment methods.