Hybrid vesicles can either form well-mixed, homogeneous membranes or textured membranes with coexisting lateral domains, providing local environments with distinct properties. Phase separation can be tuned depending on the lipid/polymer blend, temperature-dependent phase transitions of these components, the polymer architecture, degree of polymerisation and polymer molecular weight. Early work on the properties hybrid PBd-PEO giant unilamellar vesicles (GUVs) investigated the large PBd46-PEO30 polymer mixed with POPC. Mixing between these components was not ideal at low lipid composition, where it was assumed that a high energy cost for insertion of these larger polymers into a thin lipid membrane frustrated hybrid vesicle formation, and no GUVs were observed at intermediate compositions. The GUV membranes that were formed in this study were, however, homogeneous, but biotinylation of either the lipid or polymer and crosslinking by addition of the multivalent neutravidin protein did result in microscopic domain formation. The domain pattern depended on whether the polymer or lipid was biotinylated; polymer cross-linking resulted in a large single domain, while lipid cross-linking gave many small, lipid-rich domains within a polymer matrix. Further work investigating PBd46-PEO30 hybrid vesicles with saturated lipids, with and without cholesterol, also demonstrated that phase transitions of the lipid components to liquid ordered or gel phases could also drive demixing of coexisting domains in hybrid GUVs; domain sizes could be controlled by the cooling rate into the phase coexistence region from an initial well-mixed membrane at higher temperature. Phase separation has also been reported for hybrid PBd43-PEO20/DPPC GUVs. Flow cytometry analysis of nanoscale hybrid vesicles has shown that using the shorter PBd22-PEO14 polymer produces a much greater (near 100%) yield of well-mixed hybrid vesicles when blended with POPC, compared to using the larger PBd46-PEO30 polymer. GUVs with shorter block copolymers can also form heterogeneous membranes, as seen for PBd11PEO8/DPPC mixtures, where the DPPC lipids form an ordered gel phase. To aid the development of hybrid vesicles for biotechnology applications, further insight into their mixing and properties are required. Here we focus on shorter PBd-PEO block copolymers (PBd22-PEO14, MW = 1800 g.mol -1 and PBd12-PEO11, MW = 1150 g.mol -1 ) that have shown potential for incorporation of membrane proteins in mixtures with the lipid POPC, which forms fluid phases at ambient temperature and is therefore more favourable for formation of well-mixed, homogeneous membranes. Furthermore, good mixing between the PBd-PEO polymers and POPC might be expected due to a similar Hildebrand solubility parameter of the PBd block (15.9 (Jcm -3 ) 1/2 ) and the alkane tails of lipids like POPC (approx. 14-16 (Jcm -3 ) 1/2 ). In this study, we focus on the mixing and fluidity of hybrid GUVs utilising a lipid-like fluorescent probe and a fluorescently tagged block copolymer. Fluorescence recovery after photobleaching (FRAP) has previously been used to monitor membrane fluidity and viscosity for POPC/PBd46-PEO30 GUVs, where the diffusion constant of a lipid probe decreased by almost two orders of magnitude between the pure lipid and pure polymer compositions. However the impact of shorter PBd-PEO block copolymers on the fluidity of hybrid membranes is yet to be determined. To complement FRAP results, Laurdan, a membrane probe that is sensitive to the molecular packing and hydration state of the membrane, which has a strong influence on membrane fluidity, is also used to investigate the structural properties of these hybrid vesicles. While Laurdan has been employed to study the bulk properties of nanoscale PBd22-PEO14/POPC vesicles, it has not been studied with microscale spatial resolution, which might reveal heterogeneities between or within individual vesicles. Our results indicate that no phase separation occurred in our hybrid lipid/polymer blends, and that there is no statistically significant difference in membrane order between PBd22-PEO14 and PBd12-PEO11 hybrid vesicles. Membrane fluidity in both PBd22-PEO14/POPC and PBd12-PEO11/POPC hybrid GUVs was found to decrease non-linearly with increasing polymer fraction.