Owing to the convenient manufacture, transportation, low energy consumption and environ-mental impacts, lightweight concrete (LWC) has been applied as building and construction ma-terials. However, the decreased density is associated with reduction in mechanical strength. In most existing investigations, attempts have been made to improve its mechanical behaviors via supplementary cementitious or fibre materials, whereas limited studies have been implemented on the effects of nano additives, especially their synergic influence. In this study, industrial waste fly ash cenosphere (FAC) has been utilized as lightweight aggregate by 73.3% cement weight to fabricate sustainable LWC. Carbon nanotubes (CNTs) at the dosage of 0.05%, 0.15%, 0.45% and nano silica (NS) with the content of 0.2%, 0.6%, 1.0% by cement mass have been ap-plied as modifying additives. Experiments were carried out to test flexural strength, compres-sive strength and water absorption. SEM, TGA and XRD analysis were conducted to evaluate the microstructure and hydration characteristics. Based on the outcomes, the inclusion of CNTs and NS can effectively increase the flexural and compressive strength, reduce the absorbed water weight. The analysis of SEM, TG and XRD reveals that the binary usage of CNTs and NS can im-prove the pore structure and facilitate the hydration reaction.