Breast cancer is among the most prevalent type of cancer among women. Mastectomy is a common surgical option for breast cancer, which usually leads to significant functional impairment. Fatigue, anxiety and depression are reported by mastectomy patients. This study aims to investigate the effect of a multimodal exercise program on improving functional impairment, fatigue, anxiety and depression after mastectomy. A 40-year-old female presented with abnormal tissue growth, pain and nipple discharge at the right breast. She was diagnosed with invasive ductal carcinoma stage I and undertook six weeks of neoadjuvant chemotherapy followed by modified radical mastectomy (MRM). Postoperatively, patient had a functional impairment, fatigue, anxiety and depression. An eight-week multimodal exercise program comprising ROM exercises, strength and endurance training, breathing exercises and functional activities was given. DASH for assessing upper extremity functions, BFI for assessing the impact of fatigue on daily activities and HADS for assessing anxiety and depression. An eight-week multimodal exercise program effectively improves functional impairment, fatigue, anxiety and depression in mastectomy patients with rheumatoid arthritis.