Purpose The aims of this study were to investigate if/how the presence of lymphedema affects the sensation of the upper limb and to assess whether complex decongestive physiotherapy (CDP) has a favorable impact on sensory testing. Methods A total of 27 patients with unilateral stage 2 breast cancer-related lymphedema (BCRL) were included in the study. Bilateral circumferential measurements were taken with a tape measure at different levels. Based on these measurements, limb volumes were determined by summing segment volumes derived from the truncated cone formula. Circumferential measurements and ultrasonographic evaluations (epidermis, dermis, and subcutaneous fat thicknesses) were performed at 10 cm distal to the elbow crease. The Semmes-Weinstein monofilament (SWM), static and moving two-point discrimination, pressure pain threshold (PPT), and tactile localization tests were also applied at the same site. After an initial evaluation, all patients underwent CDP phase 1 program. All the evaluations were repeated at the end of the treatment period. Results Before CDP, affected sides had significantly higher values than the unaffected sides in terms of SWM (p < 0.001), static (p = 0.002) and moving (p = 0.011) two-point discrimination, PPT (p = 0.001), and tactile localization (p < 0.001) values. After CDP, SWM (p = 0.002), static (p = 0.009) and moving (p = 0.024) two-point discrimination, PPT (p = 0.014), and tactile localization (p < 0.001) values decreased significantly on the affected sides. Conclusion BCRL seems to reduce light touch, static and moving two-point discrimination, PPT, and tactile localization sensations, whereas CDP seems to improve these sensory perceptions in women with BCRL. Ultrasonographic measurements also appear to be promising for prompt and convenient follow-up in the management of BCRL.