The escalating global volume of waste from end-of-life wind turbine blades presents a significant environmental challenge, with projections indicating that approximately 2.9 million tons of this waste will require processing in Europe alone by 2050. The complex management of this waste, coupled with limited reuse options, predominantly leads to its utilization as fuel or disposal in landfills, which generates environmental concerns. This study explores the valorization of this waste through the development of a biocomposite for buildings acoustic insulation using a bio-binder. The acoustic properties of the material were evaluated by determining the sound absorption coefficient (α) and the Noise Reduction Coefficient (NRC) using the impedance tube method, and the Transmission Loss (TLn) to assess insulation performance. Samples with different bio-binder proportions (15, 20, and 25% relative to recycled fiberglass) were produced and tested. Sound absorption results were compared with commercially available materials, revealing promising and competitive performance (NRC). Transmission loss analysis demonstrated the potential of the biocomposite for acoustic insulation, with values frequently exceeding those of the reference mineral wool. The conclusions demonstrate the feasibility of producing a sustainable biocomposite for acoustic insulation in construction from wind turbine blades waste, offering an alternative solution for its management and reuse.