Purpose: To investigate the fear of falling, physical activity, and functionality in patients with lymphedema in the lower extremities. Methods: Sixty-two patients who developed stage 2–3 lymphedema in the lower extremities due to primary or secondary causes (age: 56.03 ± 7.83 years) and 59 healthy controls (age: 54.61 ± 5.43 years) were included in the study. The sociodemographic and clinical characteristics of all individuals included in the study were recorded. In both groups, fear of falling was evaluated with the Tinetti Falls Efficacy Scale (TFES), lower extremity functionality with the Lower Extremity Functional Scale (LEFS), and physical activity with the International Physical Activity Questionnaire-Short Form (IPAQ-SF). Results: There was no statistically significant difference between the demographic characteristics of the groups (p > 0.05). The primary and secondary lymphedema groups had similar LEFS (p = 0.207, d = 0.16), IPAQ (p = 0.782, d = 0.04), and TFES (p = 0.318, d = 0.92) scores. However, the TFES score of the lymphedema group was significantly higher than that of the control group (p < 0.01, d = 0.52), while the LEFS (p < 0.01, d = 0.77) and IPAQ scores (p = 0.001, d = 0.30) were significantly higher in the latter. There was a negative correlation between LEFS and TFES (r = −0.714, p < 0.001) and between TFES and IPAQ (r = −0.492, p < 0.001). LEFS and IPAQ were positively correlated (r = 0.619, p < 0.001). Conclusion: It was determined that individuals with lymphedema developed a fear of falling, and their functionality was negatively affected. This negative effect on functionality can be attributed to reduced physical activity and an increased fear of falling.