Adsorbed proteins and their conformational change on blood-contacting biomaterials play important roles in their hemocompatibility and ultimate success. Nanostructured surfaces have proven to be the next evolutionary breakthrough in controlling adsorption behavior of plasma proteins. In particular, it has been recognized that nanostructured polymeric surfaces may provide a fine-tuning mechanism to manipulate human plasma fibrinogen (HPF) assembly configuration. However, it is unclear what is the implication of the HPF conformational changes induced by nanostructured surface on both platelet adhesion and activation. In this work, through the use of HPF-pretreated nanostructured polybutene-1 (PB-1) and nanostructured polyethylene (PE) surfaces we aimed to shed light on the relationship between surface nanotopographical features and platelet response. We found that PB-1 surfaces with needle-like crystals (NLC) induce low platelet adhesion and slow activation, yet strong platelet clustering as compared to PB-1 surface with shish-kebab crystals (SKC). PE surfaces with lamellar crystals (LC) showed similar platelet adhesion as compared to PB-1 with SKCs, however the activation of platelets advanced faster leading to a high surface coverage with fully speared platelets. These findings suggest that subtle variations in surface nanotopography have a significant impact on HPF conformational change, which in turn has strong implications on platelet adhesion and activation.