<p>Calcium (Ca²⁺) is a key macronutrient crucial to the growth, development, and stress resilience of sugar crops, such as sugarcane and sugar beet. As a structural element of cell walls and membranes, Ca²⁺ is also an essential secondary messenger in numerous physiological and signalling processes. This review provides a comprehensive overview of Ca²⁺ dynamics in sugar crops, focusing on its concentration, uptake, and transport mechanisms. Its physiological function ranges from membrane stability to cell extension and enzymatic control, all of which are essential under normal and stress conditions. Ca²⁺ deficiency in sugar crops results in apparent symptoms, such as leaf tip necrosis, impaired root growth, and reduced sugar accumulation, ultimately reducing crop yield and quality. New developments in Ca²⁺ sensor proteins, including calmodulins, calcineurin B-like proteins (CBLs), and CBL-interacting protein kinases (CIPKs), underscore their significance in transducing Ca²⁺ signals under abiotic stress conditions, including drought and salinity. Furthermore, the exogenous application of Ca²⁺—through soil, foliar, or fertigation methods—has been documented to alleviate stress-induced damage by promoting antioxidative defence, osmotic balance, and nutrient uptake. The facilitatory function of Ca²⁺ in the regulation of stress-responsive genes and enhancing tolerance mechanisms is gaining prominence as a sustainable strategy in sugar crop management. This review seeks to integrate existing research on the physiological, molecular, and agronomic importance of Ca²⁺ with an emphasis on its potential as a strategic tool in promoting abiotic stress resilience in sugar crops under conditions of climate change.</p>