Yeast extract (YE) serves as a complex nutrient source and plays a pivotal role in the formation and development of microbial biofilms. This work elucidates the critical role of YE in modulating the metabolic activity of Desulfovibrio vulgaris, characteristics of passive films, and the associated microbiologically influenced corrosion (MIC) behavior of nickel (Ni). The presence of YE suppresses corrosion processes linked to extracellular electron transfer (EET) by reducing the necessity for D. vulgaris to directly extract electrons from Ni. In the absence of YE, a greater number of D. vulgaris cells adhere to the Ni surface, forming biofilms with an increased reliance on EET from Ni, thereby exacerbating localized corrosion. This is evidenced by increased weight loss, deeper pitting, and elevated localized corrosion current density, establishing a clear correlation between YE availability and the mitigation of EET-mediated MIC. Meanwhile, YE mitigates EET-driven corrosion by regulating the biofilm structure, facilitating the formation of a protective layer, and modifying the passive film on Ni. A key implication of this work is the reconsideration of YE as a universal nutrient in MIC research, emphasizing the need for caution when using YE in MIC studies that focus on EET-driven mechanisms.