Small-scale robots capable of locomotion, sensing, and interaction can have a profound impact on biomedical and environmental applications. Nevertheless, to enable the successful completion of defined tasks, small-scale robots require functional components compatible with the operating conditions. In this thesis, we develop a variety of chemically and externally powered microrobots having functional components for water remediation and targeted imaging. We initially investigate the effect of particle properties on the propulsion of chemical/light-driven hybrid microrobots—demonstrating on-demand speed control by a built-in optical brake. Then, we utilize self-propelled microrobots to remove contaminants, i.e., antibiotics and nitroaromatic compounds, by overcoming diffusion-limited reactions. The results indicate that the microrobots’ removal capacity for target contaminants can be enhanced by the embedded functional components, e.g., photoactive materials and enzymes. As another type of water remediation process, we study the collective behavior of surface-functionalized magnetic microrobots to capture free-swimming bacteria and microplastics under the influence of external magnetic fields. After concluding this chapter with a discussion on key challenges regarding the utilization of microrobots for water remediation, we introduce magnetically controlled systems for targeted imaging applications. We demonstrate that a conventional contrast agent can be equipped with magnetic properties to enable external controllability under different scenarios. Animal experiments indicate the localization of the robotic contrast agents in the gastrointestinal tract of mice to visualize the three-dimensional structure via X-ray micro-computed tomography. Moreover, we develop pH-responsive organic microrobots with magnetic response and intrinsic multi-fluorescence. Under physiologically relevant conditions, these microrobots exhibit a unique fluorescence switching behavior at different pH values to enable the monitoring of gastric acidity at target locations. These results indicate that smart imaging agents can allow untethered controllability with the aim of enhancing the capabilities of conventional imaging-based diagnosis approaches. After discussing key challenges that require interest before the translation of microrobots to the clinic, we summarize the main findings of the thesis in the last chapter. Overall, the functional microrobots presented in this thesis indicate promising features for applications in dynamic and complex scenarios as active systems.