This special issue of Neobiota focuses on Biological Invasions across freshwater, estuarine, and marine ecosystems, aiming to showcase the latest research and groundbreaking discoveries in this rapidly evolving field. The issue primarily features papers presented at the Neobiota Conference, held in Lisbon in September 2024, alongside other high-quality contributions on related topics. By bringing together diverse perspectives and novel insights, this collection seeks to deepen our understanding of invasive species dynamics, their ecological impacts, and effective management strategies in aquatic environments.