Human assistance and species’ characteristics are among the key drivers of plant invasions, which profoundly threaten ecosystem integrity, biodiversity and human well-being. However, previous studies have typically focused on one or a few factors or a particular invasion stage (e.g., naturalization) at regional scales. Here, we employed a multilevel framework to investigate the interplay between species’ characteristics (genome size, Grime’s adaptive strategies and native range size) and economic use and how these factors collectively affect plant invasion success. While our findings highlight the substantial contribution of human assistance in driving plant invasions, we also uncover the pivotal role of species’ adaptive strategies within the hierarchical network, and the influence of a specific factor that varied significantly across different invasion stages. We further revealed that the effects of genome size on plant invasions were partially mediated by other variables we tested e.g., plants with large genomes are competitors with small native range sizes but many economic uses, which all affect invasion success. Our study provides a synthesis of the multi-factor and multi-stage process of plant invasions and a deep understanding of the key drivers of plant invasions worldwide.