Purpose: To determine whether body awareness and upper extremity functionality are affected in patients with or without lymphedema development after breast cancer surgery (BCS) in comparison with individuals without a history of cancer. Methods: The study included a total of 102 individuals, including 34 who developed lymphedema after BCS (mean age: 43.88 ± 12.13 years), 34 who did not develop lymphedema after BCS (age: 44.67 ± 11.20 years), and 34 without a history of any cancer surgery (age: 45.41 ± 12.13 years). The participants’ demographic data were recorded. Body awareness was evaluated using the Body Awareness Questionnaire, and upper extremity functionality was evaluated using the Quick-Disabilities of the Arm, Shoulder, and Hand questionnaire. Results: The demographic data of the groups were similar (p > 0.05). While there were differences between the BCS groups in terms of operative time (p < 0.001) and operated breast (p = 0.001), the number of lymph nodes dissected and the type of surgery performed were homogeneously distributed (p > 0.05). Body awareness and upper extremity functionality were significantly lower in the lymphedema group than in the BCS group without lymphedema and the control group (p = 0.021 and p < 0.001, respectively). Conclusion: The development of upper extremity lymphedema after BCS adversely affects both body awareness and upper extremity functionality.