The rapid advancement of electronic devices has made thermal management a critical issue. In this study, we present phase change material (PCM)-based thermal buffering sheets that provide both heat transfer and heat delay functions. Boron nitride nanosheets (BNNS) with high aspect ratios were obtained by exfoliating bulk h-BN. The conventional exfoliation process had a low yield. In this study, the process was designed to be suitable for large-scale production. To prevent PCM leakage during phase change, paraffin was encapsulated in a silica shell formed by a TEOS-based sol-gel method. This process was conducted within an oil-water emulsion system. BNNS with negatively charged surfaces were added to the emulsion before the complete hydrolysis of TEOS, and the capsules were assembled onto the BNNS surfaces through electrostatic interaction. The resulting hybrid composite of 2D BNNS and 0D capsules was dispersed into an epoxy matrix and processed into sheet-type composites. These materials showed enhanced thermal conductivity and a delayed temperature rise under sudden heat input due to latent heat buffering. The combination of highly thermally conductive BNNS and structurally stable silica-encapsulated PCM suggests a promising direction for thermal buffering sheets that require both heat dissipation and temperature stabilization.