We sought to assess the association of breast cancer-related lymphedema (BCRL) with the ability to perform upper extremity activities of daily living (ADL) in our patient population. 324 breast cancer patients who had received treatment for unilateral breast cancer at our institution between 2005 and 2014 were prospectively screened for lymphedema. Bilateral arm measurements were performed pre-operatively and during post-operative follow-up using a Perometer. Patients completed an extensive quality of life (QOL) questionnaire at the time of each study assessment. Lymphedema was defined as a relative volume change (RVC) of ≥10% from the patient's pre-operative baseline measurement. Linear regression models were used to evaluate the relationship between post-operative arm function score (as a continuous variable) and RVC, demographic, clinical, and QOL factors. By multivariate analysis, greater fear of lymphedema (p < 0.0001), more pain (p < 0.0001), body mass index >25 (p = 0.0015), mastectomy (p = 0.0001), and having an axillary node dissection (p = 0.0045) were all associated with lower functional scores. Higher emotional well-being score (p < 0.0001) and adjuvant chemotherapy (p = 0.0005) were associated with higher post-operative functional score. Neither low-level volume changes (5-10 % RVC) nor BCRL (RVC ≥10 %) were associated with ability to perform upper extremity ADL as measured by self-report (p = 0.99, p = 0.79). This prospective study demonstrates that low-level changes in arm volume (RVC 5-10 %) as well as clinically significant BCRL (RVC ≥10 %) did not impact the self-reported ability to use the affected extremity for ADL. These findings may help to inform clinicians and patients on the importance of prospective screening for lymphedema and QOL which enables early detection and intervention.