Adopting sustainable materials is a pressing concern for the construction industry to achieve net-zero carbon emissions, driving ongoing research to address environmental challenges. With a particular focus on the fibre-reinforced polymer (FRP) byproducts and wastes generated by various industries, this paper investigates the viability of pulverising and repurposing waste materials from electrical cross-arms and aerospace composite parts in cementitious materials as a partial substitute for cement. Micro fibres with crushed resin particles (passing through a 600 μm sieve) were incorporated into the mortar, up to 10 % relative to the mass of cement. A series of tests was conducted to evaluate the effects of varying FRP recyclates on the mechanical, durability and electrical performance of mortars. The results indicated that at the 28-day curing age, the inclusion of FRP recyclates led to a 19 % reduction in water absorption and significant enhancement in the compressive (up to 67 %) and flexural strength (up to 43 %). The optimal restraint of drying shrinkage was observed when replacing 5 % by weight of cement with FRP recyclates from electrical cross-arms. The inclusion of FRP recyclates from aerospace offcuts resulted in a 25 % reduction in electrical resistivity, indicating a potential for reusing aerospace recyclates for electrically conductive cementitious composites (ECCCs). Further analyses were conducted to assess the effects of FRP recyclate addition on the microstructural properties of the cementitious matrix. This research offers a promising pathway to repurpose composite wastes from utility and aerospace industries as valuable additions to construction materials.