Fluorophore diffusion measurements provide information on the viscosity and dynamics in hybrid membranes. The diffusion of both the lipid-like DiO probe and PBd22-PEO14 -TMR probe decrease with increasing block copolymer content in the GUVs. The smaller lipid probe diffuses faster than the polymer probe, as would be anticipated, and the membranes containing the shorter PBd12-PEO11 polymer also facilitate faster lateral diffusion in the membrane. The decrease in lateral diffusion is not directly proportional to the polymer composition in the membrane. Notably, the diffusion in PBd22-PEO14-containing mixtures is strongly impacted by a minority composition of the polymer in the membrane.