The formation of hybrid crystalline materials based on organic and inorganic components is of considerable interest due to their structural diversity and potential applications in agrochemical and functional materials. In this work, the physicochemical interactions and phase equilibria in the ternary aqueous system Ca(ClO₃)₂·2CO(NH₂)₂ – CH₂ClCOOH·(C₂H₄OH)₃N – H₂O were systematically investigated over a temperature range from −24 to 60 °C. The study was carried out using the visual-polythermal method, which allowed the determination of solubility relationships and the construction of a complete polythermal phase diagram of the system. Analysis of the phase diagram revealed several crystallization regions corresponding to ice, Ca(ClO₃)₂·2CO(NH₂)₂·2H₂O, CH₂ClCOOH·(C₂H₄OH)₃N, and a newly formed crystalline phase with the composition CH₂ClCOOH·Ca(ClO₃)₂·(C₂H₄OH)₃N. The presence of a distinct crystallization field for this compound indicates the formation of a stable individual hybrid crystalline material in the studied system. The compound was isolated from solutions corresponding to its crystallization domain and subjected to chemical and physicochemical characterization. Elemental analysis results showed good agreement between experimental and calculated values for calcium, chlorate ions, and nitrogen, confirming the proposed stoichiometric composition. Infrared spectroscopy further supported the formation of the new hybrid compound. The spectra revealed characteristic vibrational bands associated with chlorate ions and carboxylate groups, as well as changes in the hydroxyl and amino group vibrations, indicating structural reorganization during complex formation. The obtained results demonstrate that the investigated system forms a stable organic–inorganic hybrid crystalline compound under specific temperature and concentration conditions. The constructed phase diagram provides valuable information on crystallization boundaries and phase stability. These findings contribute to a deeper understanding of intermolecular interactions and phase behavior in multicomponent aqueous systems and may serve as a physicochemical basis for the development of new complex-action defoliants and functional crystalline materials.