The development of biodegradable polymeric materials with tunable properties and suitable processability has stimulated increasing interest in the use of polymer blends and nanofillers as an effective approach to achieving desirable structural and surface characteristics. In this study, the effects of poly(lactic acid) (PLA), polypropylene (PP), polypropylene-grafted-maleic anhydride (PP-g-MA), and graphene oxide (GO) on the thermal and surface properties of the resulting nanocomposites were investigated. Samples with different compositions were prepared, and their thermal behavior was evaluated using differential scanning calorimetry (DSC). In addition, the morphological and surface characteristics of selected samples were investigated using atomic force microscopy (AFM) and water contact angle measurements, respectively. The DSC results showed that variations in component composition significantly affected the melting enthalpy and degree of crystallinity of the PLA and PP phases, whereas the melting temperature varied within a relatively narrow range. The crystallinity of the PLA phase ranged from 26.84% to 42.69% among the investigated samples, while increasing GO content did not produce a uniform trend in Xc, indicating the competing effects of heterogeneous nucleation and restriction of polymer-chain mobility. AFM images revealed changes in surface morphology associated with variations in composition and the presence of the compatibilizer. Contact angle measurements showed values ranging from 77.61° to 83.11°, confirming changes in surface wettability with nanocomposite composition. Overall, the results demonstrated that the simultaneous adjustment of blend composition and GO content plays an important role in controlling the thermal behavior, morphology, and surface properties of the nanocomposite materials.