This study explores the synthesis and multifaceted applications of a novel Schiff base ligand, (HYD) (1E,2E)-N-(4-methoxyphenyl)-1-(2-(p-tolyl)hydrazono)propan-2-imine, and its binary complexes with cobalt (II) and copper (II) ions. The compounds were extensively characterized using various spectroscopic and analytical techniques. Density Functional Theory (DFT) calculations suggested a distorted octahedral geometry for these complexes. The antimicrobial properties of the synthesized compounds were evaluated against a range of bacterial and fungal strains, with the copper (II) complex exhibiting superior efficacy. The antitumor potential was assessed against MCF-7 breast carcinoma cells. Molecular docking simulations provided insights into the binding interactions with protein receptors (7DAF), informing future inhibition studies. This research introduces a nanotechnology-based approach for detecting cadmium pollution in environmental samples. The nanostructured copper (II) Schiff base complex was analyzed using advanced techniques, including XRD, SEM, AFM, and BET surface area analysis. A quartz crystal microbalance (QCM) sensor incorporating this nano complex demonstrated high sensitivity in detecting Cd(II) ions in groundwater and industrial effluent wastewater samples, with rapid results obtained in under 5 minutes. The sensitivity of the QCM-based sensor was investigated under various pH levels and temperatures, showcasing its versatility in different environmental conditions. Additionally, the cytotoxic effects of nanoparticles derived from the copper (II) Schiff base complex were studied to assess their biocompatibility. This comprehensive study highlights the versatile applications of the synthesized compounds as potential antimicrobial and anticancer agents, as well as their promising role in developing sensitive, efficient nanosensors for rapid and accurate environmental cadmium detection. The research underscores the potential of integrating nanotechnology with traditional chemical approaches to address pressing environmental and health challenges.