Objective Our study examines the financial cost of lymphedema following a diagnosis of breast cancer and addresses a significant knowledge gap regarding the additional impact of lymphedema on breast cancer survivors. Methods An online national survey was conducted with 361 women who had either breast cancer without lymphedema (BC) (group 1, n = 209) or breast cancer with lymphedema (BC+LE) (group 2, n = 152). Participant recruitment was supported by the Breast Cancer Network Australia and the Australasian Lymphology Association. Results Both breast cancer and lymphedema result in significant out‐of‐pocket financial costs borne by women. Of patients with BC+LE, 80% indicated that their breast cancer diagnosis had affected them financially compared with 67% in the BC group (P < .020). For patients with lymphedema, over half (56%) indicated that this specific additional diagnosis to their breast cancer affected them financially and that costs increased with lymphedema severity. The cost of compression garments formed a large proportion of these costs (40.1%). The average number of attendances to a therapist each year was 5.8 (range, 0‐45). Twenty‐five patients (16.4%) had an episode of cellulitis in the past year. The incidence of cellulitis was 7.7% in 91 patients with subclinical or mild lymphedema compared with 29.5% of 61 patients with more extensive lymphedema (P < .001). The average out‐of‐pocket financial cost of lymphedema care borne by women was A$977 per annum, ranging from A$207 for subclinical lymphedema to over A$1400 for moderate or severe lymphedema. Conclusions This study identifies an additional detrimental effect of lymphedema on women in terms of financial costs.