<p>In this study, resorcinol–furfural aerogel resins were synthesized and the optimal crosslinking ratio was determined to obtain a stable three-dimensional porous network. Following optimization, the resorcinol–furfural resin was chemically modified with phenylboronic acid at different weight ratios to introduce boron-containing functionalities into the polymeric framework. The aim was to tailor the structural, textural, and thermal properties of the aerogels through controlled boron incorporation. Fourier transform infrared spectroscopy confirmed the successful interaction between phenylboronic acid and the resorcinol–furfural network through the formation of B–O–C and B–O–B linkages. Nitrogen adsorption–desorption analysis revealed that boron incorporation significantly influenced the surface area and pore structure, with changes attributed to variations in crosslinking density and network evolution. Thermal analyses demonstrated enhanced thermal stability of the modified aerogels compared to the unmodified resorcinol–furfural resin. The results establish a clear structure–property relationship between boron content, network architecture, and thermal behavior, highlighting the potential of phenylboronic acid-modified resorcinol–furfural aerogels for advanced high-temperature and thermally stable material applications.</p>