High fruit and vegetable consumption is associated with a lower risk of breast cancer. The incidence of breast cancer is continuously increasing in Korea, but only a few studies on nutrition intervention in breast cancer patients has been reported. The aim of this study was to investigate whether an 8-week nutrition intervention based on dietary counseling can promote fruit and vegetable consumption, increase serum antioxidant nutrient levels, and improve quality of life in Korean breast cancer patients. Sixty-one breast cancer patients received either standard care (n = 31) or nutrition counseling (n = 30). The standard care group was given brochures recommending phytochemical rich diet. The intervention group was provided with two nutrition counseling sessions and one cooking class session, thereby encouraged subjects to eat at least 10 or more servings of fruits and vegetables per day. After 8-week intervention, waist circumference in the intervention group was significantly decreased (p < 0.001) even though no difference was reported for body mass index. Energy intake (p = 0.007), fiber (p < 0.001), and antioxidant nutrient (vitamin A, C, E, and β-carotene, p < 0.001, respectively) intakes were significantly increased. Serum antioxidant level was also increased significantly, i.e., vitamin A (p = 0.048); vitamin E (p = 0.004). Total vegetable intake (excluding kimchi intake) in the intervention group was increased from 425 g to 761 g (p < 0.001), fruit consumption was also increased from 232 g to 334 g (p < 0.001), while standard care group did not show any significant change. Our study showed that nutrition counseling and providing cooking tips helped to encourage the patient to consume and maintain more fruit and vegetable intakes.