A new platinum(II) complex containing ethylenediamine (En) and etidronate (Et) ligands was successfully synthesized and fully characterized. Etidronic acid (HEDP), also known as 1-hydroxyethylidene-1,1-diphosphonic acid, was first prepared and confirmed through a combination of spectroscopic analyses, including 31P NMR, ¹H NMR, infrared (IR), and Raman spectroscopy. To enable its coordination to the platinum center, the free acid was neutralized with a stoichiometric amount of sodium hydroxide, yielding its disodium salt form, which exhibits higher solubility and stability in aqueous media. Subsequently, the desired complex [Pt(En)(Et)] was synthesized via a two-step substitution process: first, the chloride ligands in [Pt(En)Cl2] were replaced by nitrate ions under mild conditions, and then the nitrate groups were displaced by the etidronate ligand to yield the target bisphosphonate complex. The product was isolated as a stable, water-soluble solid, and its composition and coordination environment were confirmed by spectroscopic methods. The combination of both the ethylenediamine chelating agent and the etidronate ligand results in a coordination framework that enhances the chemical stability and water Solubility of the platinum center. These features make the synthesized complex a promising structural prototype for further exploration in medicinal and biomineral chemistry, especially in the development of platinum-based therapeutic and diagnostic agents. The unique combination of stability, solubility, and potential biological activity provides valuable insights into the design of new classes of bioactive platinum(II)-bisphosphonate compounds with improved functional properties.