The present study investigates the possibility of developing a self-compacting lightweight mortar (SCLM) using an agricultural by-product, namely the Crushed Olive Kernel (COK) Shell. The valorization of these co-products can certainly make it possible to use them as a substitute for natural aggregates and thus create additional economic, social and environmental value; it also allows a better handling and management of these co-products. COK shells are used in this study as partial replacement of sand, at different rates, i.e. 0, 25, 50, 75 and 100%. The influence of aggregates content on the physical, mechanical and thermal characteristics of the new materials is studied, analyzed and evaluated. Since these new materials have lower thermal conductivities than that of reference mortar, they can successfully be used as substitutes for natural sand in building materials. The results obtained support the possibility of manufacturing SCLM with a 28-day compressive strength of 9.58 MPa at a 100% COK substitution rate and a thermal conductivity of 0.326 W/m.K. The flexural strength, ultrasonic pulse velocity (UPV) and modulus of elasticity (Ed) were reduced by 61%, 51% and 85%, respectively as compared to those of the reference mortar (SCMO). It is also apparent from this study that COKs are light aggregates that allow formulating light self-compacting mortars with a density between 1400 and 1900 kg/m3.