Cell mechanics significantly influence cell-environment interactions and fundamental cellular functions such as growth, motility, and phagocytosis. Alveolar macrophages are a type of immune cell found in the alveoli of the lungs that are responsible for the removal of pathogens and help mediate inflammatory responses. Patients with severe lung inflammation are often treated with high levels of inhaled oxygen. This study investigates the effects of hyperoxia on the morphology and mechanical properties of alveolar macrophages. We test the hypothesis that structural changes due to hyperoxia exposure result in measurable differences in cell elasticity. Atomic force microscopy (AFM) and confocal laser scanning microscopy (CLSM) are used to measure changes in cell elasticity through force-indentation measurements and fluorescence imaging of cytoskeletal structure, respectively. Cells are harvested from C57BL/6 J mice, isolated, plated in glass-bottomed dishes, and immediately subjected to either hyperoxic (90% oxygen) or normoxic conditions for 2 h or 24 h. Initial observations reveal a decrease in cell stiffness at 24 h relative to 2 h, regardless of the environmental oxygen condition. Cytoskeletal rearrangement and the emergence of filopodia are observed. These structural adaptations, especially the presence of filopodia, are likely to influence the phagocytic activity of the alveolar macrophages, underscoring the potential impact of the oxygen environment on cellular functions.