Plant growth-promoting fungi (PGPF) are emerging as key bioagents in the shift toward ecologically intensive and sustainable agriculture. These beneficial fungi exhibit a broad spectrum of functional traits that enable direct modulation of plant physiology, thereby enhancing growth and productivity. PGPF contribute to plant development through the biosynthesis of indole-3-acetic acid (IAA), phosphate solubilization, siderophore-mediated iron acquisition, and activation of stress-responsive antioxidant systems. This chapter provides a mechanistic overview of these interactions, emphasizing the role of PGPF in facilitating nutrient mobilization, supporting rhizospheric stability, and promoting overall plant health. However, significant challenges persist in translating their efficacy from controlled environments to field conditions. Variability in performance is often attributed to soil heterogeneity, climatic fluctuations, and genotype-strain incompatibilities. Additional barriers such as formulation instability, reduced spore viability during storage, and the absence of clear regulatory frameworks further hinder large-scale application. To overcome these constraints, the chapter advocates for an integrative strategy combining omics-driven strain improvement, region-specific formulations, and inclusive policy frameworks for biofertilizer development. Overall, the chapter underscores the potential of PGPF in advancing resilient, nutrient-efficient, and low-input agricultural systems.