Oleogels, which exhibit solid-like rheological behavior and high levels of unsaturated fatty acids, are considered promising alternatives to conventional solid fats. This study systematically examined the effects of glyceryl monostearate (GMS) and glyceryl distearate (GDS) as oleogelators on the gel structure and properties of high oleic peanut oil (HOPO), and further evaluated their application in walnut cookies as potential substitutes for lard. The findings revealed that at equivalent addition levels, the GMS-HOPO exhibited significantly superior plasticity, oil-binding capacity, and solid fat content compared to the GDS-HOPO. With increasing concentrations of GMS or GDS, the melting peak temperatures of the oleogels rose from 44.96 ℃ to 54.24 ℃ and from 26.90 ℃ to 31.90 ℃, respectively. Rheological analyses further indicated that both the molecular architecture of the gelators and their concentration collectively governed the temperature-responsive behavior of the gels. In walnut cookie applications, the granular crystals formed by GDS contributed to a more crumbly texture, whereas GMS promoted the formation of needle-like or lamellar crystalline structures. Notably, the 8% GDS-HOPO, with its moderate solid fat content and appropriate thermal response, facilitated the development of a desirable porous structure in the dough. This effectively modulated the Maillard reaction, leading to a uniform golden-brown coloration (L* = 67.34, a* = 4.64, b* = 26.97) in the final product. Moreover, the overall hardness (6 143.30 g) and textural attributes of the 8% GDS-HOPO walnut cookies were comparable to those of the traditional lard-based formulation, underscoring its potential for developing low-saturated fat bakery products with practical relevance.