Metal-doped carbon dots (M-CDs) are brand-new 0-D nanomaterial that affords multiple guaranteed properties because of metals in between tiny carbon matrices. However, preparing M-CDs without aggregation of metals is very challenging. Here, we proposed a new tactic method to prepare highly water-soluble ruthenium Ru(Ⅱ)-holding CDs (Ru@CDs) through a one-step microwave-assisted approach with quantum yield of 19.21% using ruthenium chloride and ethylene diamine without any solvents. The optical, surface, structural, and morphological features were deeply evaluated with the support of UV–vis, photoluminescence, Fourier-transform infrared, Raman, X-ray diffraction, transmission electron microscope, and X-ray photoelectron spectroscopy techniques. The excellent photoluminescent and water-soluble properties of Ru@CDs were employed to individually detection of dual carcinogenic environmental toxic metal ions through the photoluminescence technique. They detected the lower limit of 0.128 μM as Cr6+ and 0.328 μM as Hg2+ in the aqueous environment, which was very low compared to CDs. Followed by Ru@CDs, embedded cost-efficient filter paper was fabricated for real-time visual recognition of Cr6+ and Hg2+ ions in water. Significantly, Ru@CDs show good cytotoxicity and effective growth inhibition against cancer cells compared to CDs. So, the Ru@CDs were employed as an effective bioimaging agent selectively. To conclude, facile synthesized Ru@CDs explore its multifunctional quality as a better environmental pollutant detector and bioimaging agent.