Roads play a major role in successful biological invasions of plants, animals (vertebrates and invertebrates), and microorganisms (e.g., fungi). They are an important pathway for the dispersal of non-native organisms across the landscape from where they can spread into adjacent agricultural and less-disturbed ecosystems. In most cases, the spread of plants, smaller animals, and microbes is strongly facilitated by humans, carrying dispersal units on their vehicles, equipment, animals, and clothes. Roadsides have homogenous environmental conditions compared with adjacent habitats, and the disturbance caused by maintenance practices provides resources that many non-native species, especially plants, benefit from. As the number and wealth of the global human population increases, so too will traffic, tourism, and recreation, further enhancing the movement and establishment of new species to remote and protected areas including high elevation and latitude regions. Here, we synthesize the evidence of roads as drivers of biological invasions, and highlight avenues for future research, including studies on insect and microbial organism movement along roads, traits that infer successful establishment, and how road invasions might be augmented through trophic interactions.