Chitosan coatings could effectively increase the biostability and biocompatibility of biomaterials while maintaining their structural integrity. In this study, electrospun fibrous polyhydroxybutyrate (PHB) membranes were pre-treated with potassium hydroxide (KOH) or hydrogen peroxide (H2O2) and then modified with dopamine (DA) and glutaraldehyde (GA) to improve their adhesion with chitosan (CS). Scanning electron microscopy (SEM), water contact angles (WCA), and Fourier transform infrared spectroscopy (FTIR) were used to demonstrate the successful generation of DA and GA-modified PHB fibers. KOH pre-treated PHB membranes exhibited superior binding efficiency with CS at low concentrations compared to their H2O2 pre-treated counterparts. The thermal analysis demonstrated a considerable decrease in the degradation temperature and crystallinity of KOH pre-treated membranes, with temperatures dropping from 309 °C to 265.5 °C and crystallinity reducing from 100% to 25.59% as CS concentration increased from 0 to 2 w/v%. In comparison, H2O2 pre-treated membranes experienced a mild reduction in degradation temperature, from 309 °C to 284.4 °C, and a large decrease in crystallinity from 100% to 43%. UV-vis analysis using Cibacron Brilliant Red 3B-A dye (CBR) indicated similar binding efficiencies at low CS concentrations for both pre-treatments, but decreased stability at higher concentrations for KOH pre-treated membranes. Mechanical testing revealed a considerable increase in Young’s modulus (2 to 14%), toughness (31 to 60%), and ultimate tensile stress (UTS) (14 to 63%) for KOH-treated membranes compared with H2O2 pre-treated membranes as CS concentration increased from 0 to 2 w/v%.