Since long, oxidative stress-driven modifications in breast cancer were faced as detrimental cellular events that cause obligatory cell damage. Recent studies show that the products generated during redox reactions are able to modulate pivotal processes regarding breast cancer survival, proposing a new way of looking at the events linked to oxidative stress. Therefore, it is necessary to understand the basis of oxidative stress generation in breast cancer by reviewing the two most important events that perpetuate the malignant transformation: mitochondrial dysfunction and DNA damage/misguided repair. In this context, the present review addresses the main events related with redox events reported in breast cancer studies, highlighting the impact of the oxidative environment on DNA damage and the role of the mitochondria as a determinant of oxidative modifications. In addition, we further discuss the main stand-out findings concerning the modulatory role of the metabolites derived from redox stresses, with a special focus on the oxidative changes detected in the breast cancer microenvironment and its systemic impact.