Lifestyle-based changes such as diet, physical inactivity, smoking, and alcohol consumption are some key risk factors of breast cancer among women. Changes in the lifestyle disrupt redox homeostasis, particularly decreasing the ability of the body to detoxify harmful free radicals. Therefore, an imbalance between these finely tuned mechanisms results in the formation of excessive reactive oxygen species (ROS). These elevated levels of ROS may promote breast cancer development and progression. Over the centuries, the way of living has changed drastically worldwide, and several lifestyle factors have evolved as a threat and risk factor for cancer in humans. Most of these lifestyle factors, e.g., smoking, alcohol consumption, physical inactivity, poor nutrition, etc., have been associated with the rise in breast cancer incidences globally. A large number of accumulating evidence from clinical and epidemiological studies strongly suggest the link between lifestyle factors and the incidence of breast cancer in women. Some changes in lifestyles increase the risk of breast cancer in both premenopausal and postmenopausal women. However, the period between menarche to the birth of the first child is the most vulnerable phase in women's lives. Lifestyle factors drive carcinogenesis through various mechanisms. Among them, ROS-mediated oxidative damage plays a significant role in breast cancer development. Here, in this chapter, we have discussed the most relevant lifestyle factors associated with breast carcinogenesis in women. Also, we have discussed how these lifestyle factors modulate redox homeostasis to elicit oxidative damage-induced carcinogenesis. A better understanding of the association between lifestyle factors and breast cancer may enable us to identify critical factors that can play a significant role in breast carcinogenesis.