Controlling protein adsorption on biomaterial surfaces requires a thorough understanding of interfacial phenomena. Proteins adhering after implantation influence successful biointegration. Deciphering adsorption mechanisms at biointerfaces is crucial and of high interest. Here, a combination of time-resolved in situ electrokinetic measurements and quartz crystal microbalance with dissipation monitoring (QCM-D) was employed to understand the adsorption phenomena of blood proteins at thin layers of polysaccharide-based biointerfaces. Adsorption kinetics of bovine serum albumin (BSA), fibrinogen (Fg), and γ-globulin (γG) was studied on polydimethylsiloxane (PDMS) coatings functionalised with chitosan-surfactant complex and hyaluronic acid. The functionalised surfaces show a suppressed protein affinity compared to hydrophobic PDMS. Fg exhibits peculiar adsorption behaviour on PDMS, stemming from the highly oriented end-on adsorption with freely moving α chains. BSA demonstrates arbitrary surface orientation, while γG shows preferential surface orientation on PDMS, exposing a higher density of cationic moieties. The combination of the mentioned techniques proved beneficial for the investigation of interactions, orientations, and changes at biointerfaces in real-time. The approach is versatile and promising where research on surfaces and interfaces is in high demand.