Diffuse pulmonary lymphangiomatosis (DPL) is a rare disease caused by uncontrolled lymphatic vessel proliferation resulting in respiratory dysfunction. Lymphatic vessel growth is influenced by vascular endothelial growth factor (VEGF). It has been shown that bevacizumab, a monoclonal antibody to VEGF type A, may be helpful in treating diseases characterized by excessive vessel proliferation. We report the case of a 51-year-old man with DPL treated with 1 mg/kg bevacizumab every three weeks for 6 months. A significant improvement in lung infiltrates was seen on post-treatment computed tomography (CT) chest with a 17.5% improvement in forced expiratory volume in one second (FEV1). The patient reported improved respiratory symptoms, and no significant adverse drug side effects were reported. The authors believe this is the first case of DPL to report lung function improvement [FEV1, forced vital capacity (FVC), and Diffusion Capacity for Carbon Monoxide (DLCO)] following bevacizumab therapy.