The benefit of exercise for breast cancer-treated women is well documented. However, studies of cardiovascular fitness training for women with breast cancer-related arm lymphedema are rare. The purpose of this study was to investigate the effects of intensive pole walking on arm lymphedema in women treated for breast cancer. Thirty-five women with unilateral lymphedema were included and twenty-three completed an eight-week exercise intervention consisting of pole walking 3-5 times per week, for 30-60 min, at 70%-80% of their maximum heart rate, preceded by a two-week control period. Measurements of arm lymphedema (water displacement method), body weight, cardiovascular fitness (sub-maximal bicycle ergometer test) and subjective assessments (disability of the arm, shoulder and hand (DASH) questionnaire; heaviness and tightness using a visual analogue scale (VAS); and well-being) were performed before the control period and before and after the exercise intervention. The results indicated a significant reduction in total arm volume of the lymphedema arm (p = 0.001), in lymphedema absolute volume (p = 0.014) and lymphedema relative volume (p = 0.015). Significant decreases of heart rate (p = 0.004), DASH score (p = 0.053) and rating of tightness in the arm (p = 0.043) were found. Positive and negative influences on well-being were reported. The conclusion of this study is that pole walking is feasible for breast cancer-treated women with arm lymphedema.