Floating islands have been commonly utilized for the ecological remediation of urban waters; meanwhile, they are beneficial to landscape decoration and beauty improvement. Therefore, this work was conducted to analyze the roles of floating islands in water purification, urban aesthetics, and the potential association. Based on this, different plant-based floating islands were constructed and employed for the treatment of lake water, and biochar was utilized as fillers for the coordination and the capacity enhancement, which fulfilled the synergism of plants, biochar, and the attached microbes. Furthermore, specific effects of floating islands on the improvement of urban aesthetics were analyzed from different perspectives, and the corresponding thinking was proposed for the designing and the optimization, including plants collocation, spatial layout, cultural background, and contact with nature. This work offers a new insight into the construction of floating islands to realize the water purification and strengthen the beauty of urban landscapes, and thus improving the living environment quality of human beings on the whole.