<p>Liquid-based direct exfoliation (LDE) has become a highly attractive top-down route for producing hexagonal boron nitride (h-BN) nanomaterials in a scalable and cost-efficient manner. In contrast to bottom-up techniques such as chemical vapor deposition or solvothermal growth, which provide excellent crystallinity but remain limited by high cost and low throughput, liquid-based direct exfoliation allows the production of boron nitride nanosheets (BNNSs) while retaining their original chemical stability, electrical insulation, and layered crystalline structure. However, achieving high-yield, maintaining large lateral size, and selecting exfoliation solvent continue to pose significant challenges that hinder industrial transformation. This review offers a comprehensive examination of the production methods and applications that govern exfoliation efficiency across direct ultrasonic, polymer-assisted, functionalization-hybridization, and metal-assisted strategies. Quantitative performance comparisons highlight how cavitation dynamics, solvent solute compatibility, and interfacial stabilization dictate flake thickness, yield, and dispersion stability. The technological relevance of LDE h-BN is further demonstrated through its dramatically expanding applications in thermal interface materials, dielectric layers, energy systems, lubrication, and emerging optoelectronic platforms. By integrating insights from materials chemistry and process engineering, this review outlines clear objective assessment and future opportunities for enabling high-yield, sustainable, and industrially viable production of h-BN nanomaterials.</p> Graphical abstract <p></p>